Player data updated: 2026-09-01 02:16 UTC

Stefan Kozlov

USA Age 28 183 cm / 6'0" Plays: Right-Handed ATP Tour years active: 2013–2022

Stefan Kozlov represented the United States on the ATP Tour and reached a career-high ranking of No. 103. In TennisDB's records, Stefan Kozlov finished with a career record of 9–26 and no singles titles.

Peak ranking

103 (Jul 18, 2022)

Elo peak

1674 (49th percentile)

Career record

9–26 (25.7%)

Career titles

Prize money

$1,131,991

Records cover recorded main-draw singles results in TennisDB's ATP event archive, including credited walkovers; qualifying is shown separately below.

Jump to section

ATP Matches full match log →

Stefan Kozlov's recent, live, and scheduled ATP matches
Opponent	Score	Result	H2H	Match Data	Date	Round	Tournament	Category	Surface
Zachary Svajda #73	5-7 1-6	L	H2H	Match data	Jul 25, 2026	Q1 Q	Washington Open	ATP 500	Hard
Patrick Kypson #105	6-7(3) 0-6	L	H2H	Match data	Feb 21, 2026	Q1 Q	Mexican Open	ATP 500	Hard
Nishesh Basavareddy #106	2-6 4-6	L	H2H	Match data	Feb 24, 2025*	Q2 Q	Mexican Open	ATP 500	Hard
Duarte Vale #474	6-1 6-4	W	H2H	Match data	Feb 24, 2025*	Q1 Q	Mexican Open	ATP 500	Hard
Zachary Svajda #169	3-6 0-6	L	H2H	Match data	Feb 10, 2025*	Q1 Q	Delray Beach Open	ATP 250	Hard

Qualifying matches are shown here but excluded from main-draw summaries and leaderboards.

Rivals all rivalries →

Stefan Kozlov's most-played ATP rivals
Opponent	W	L	M	Last Played	H2H
Steve Johnson	3	2	5	Jul 14, 2022	H2H
Sam Querrey	0	2	2	Aug 15, 2017	H2H
Donald Young	0	2	2	Mar 11, 2017	H2H
J.J. Wolf	0	1	1	Sep 22, 2022	H2H
Daniil Medvedev	0	1	1	Aug 31, 2022	H2H

Career Results

Stefan Kozlov career results by season
Season	Age	Type	W	L	M	Win %	Start Rank	End Rank
2013	15	ATP	0	1	1	0.0%	1,402	1,083
2014	16	Qualifying Q	1	4	5	20.0%	—	—
2014	16	ATP	0	1	1	0.0%	1,081	467
2015	17	Qualifying Q	0	2	2	0.0%	—	—
2015	17	ATP	0	2	2	0.0%	466	351
2016	18	Qualifying Q	1	5	6	16.7%	—	—
2016	18	ATP	3	2	5	60.0%	351	116
2017	19	Qualifying Q	9	6	15	60.0%	—	—
2017	19	ATP	2	9	11	18.2%	116	167
2018	20	Qualifying Q	5	7	12	41.7%	—	—
2018	20	ATP	0	1	1	0.0%	167	316
2019	21	Qualifying Q	0	1	1	0.0%	—	—
2020	22	Qualifying Q	1	1	2	50.0%	—	—
2020	22	ATP	0	1	1	0.0%	431	371
2021	23	Qualifying Q	5	3	8	62.5%	—	—
2021	23	ATP	0	1	1	0.0%	374	159
2022	24	Qualifying Q	6	10	16	37.5%	—	—
2022	24	ATP	4	8	12	33.3%	159	198
2023	25	Qualifying Q	1	5	6	16.7%	—	—
2024	26	Qualifying Q	0	2	2	0.0%	—	—
2025	27	Qualifying Q	1	2	3	33.3%	—	—
2026	28	Qualifying Q	0	2	2	0.0%	—	—
Career		—	9	26	35	25.7%	—	—

Career Results by Surface

Stefan Kozlov career results by season and surface
Season	Age	Type	Hard				Clay				Grass				Total
Season	Age	Type	W	L	M	Win %	W	L	M	Win %	W	L	M	Win %	W	L	M	Win %
2013	15	ATP	—	—	—	—	—	—	—	—	0	1	1	0.0%	0	1	1	0.0%
2014	16	Qualifying Q	1	4	5	20.0%	—	—	—	—	—	—	—	—	1	4	5	20.0%
2014	16	ATP	0	1	1	0.0%	—	—	—	—	—	—	—	—	0	1	1	0.0%
2015	17	Qualifying Q	0	2	2	0.0%	—	—	—	—	—	—	—	—	0	2	2	0.0%
2015	17	ATP	0	2	2	0.0%	—	—	—	—	—	—	—	—	0	2	2	0.0%
2016	18	Qualifying Q	1	2	3	33.3%	0	1	1	0.0%	0	2	2	0.0%	1	5	6	16.7%
2016	18	ATP	—	—	—	—	—	—	—	—	3	2	5	60.0%	3	2	5	60.0%
2017	19	Qualifying Q	5	4	9	55.6%	1	1	2	50.0%	3	1	4	75.0%	9	6	15	60.0%
2017	19	ATP	0	6	6	0.0%	—	—	—	—	2	3	5	40.0%	2	9	11	18.2%
2018	20	Qualifying Q	2	5	7	28.6%	2	1	3	66.7%	1	1	2	50.0%	5	7	12	41.7%
2018	20	ATP	—	—	—	—	0	1	1	0.0%	—	—	—	—	0	1	1	0.0%
2019	21	Qualifying Q	0	1	1	0.0%	—	—	—	—	—	—	—	—	0	1	1	0.0%
2020	22	Qualifying Q	1	1	2	50.0%	—	—	—	—	—	—	—	—	1	1	2	50.0%
2020	22	ATP	0	1	1	0.0%	—	—	—	—	—	—	—	—	0	1	1	0.0%
2021	23	Qualifying Q	5	3	8	62.5%	—	—	—	—	—	—	—	—	5	3	8	62.5%
2021	23	ATP	0	1	1	0.0%	—	—	—	—	—	—	—	—	0	1	1	0.0%
2022	24	Qualifying Q	4	6	10	40.0%	0	1	1	0.0%	2	3	5	40.0%	6	10	16	37.5%
2022	24	ATP	4	6	10	40.0%	—	—	—	—	0	2	2	0.0%	4	8	12	33.3%
2023	25	Qualifying Q	1	5	6	16.7%	—	—	—	—	—	—	—	—	1	5	6	16.7%
2024	26	Qualifying Q	0	1	1	0.0%	0	1	1	0.0%	—	—	—	—	0	2	2	0.0%
2025	27	Qualifying Q	1	2	3	33.3%	—	—	—	—	—	—	—	—	1	2	3	33.3%
2026	28	Qualifying Q	0	2	2	0.0%	—	—	—	—	—	—	—	—	0	2	2	0.0%
Career	—	—	4	17	21	19.0%	0	1	1	0.0%	5	8	13	38.5%	9	26	35	25.7%

Career Results by Opponent Rank

Stefan Kozlov career results by season and opponent rank
Season	Age	1-10				11-30				31-100				100+				Total
Season	Age	W	L	M	Win %	W	L	M	Win %	W	L	M	Win %	W	L	M	Win %	W	L	M	Win %
2013	15	0	0	—	—	0	0	—	—	0	0	—	—	0	1	1	0.0%	0	1	1	0.0%
2014	16	0	0	—	—	0	0	—	—	0	1	1	0.0%	0	0	—	—	0	1	1	0.0%
2015	17	0	0	—	—	0	0	—	—	0	1	1	0.0%	0	1	1	0.0%	0	2	2	0.0%
2016	18	0	0	—	—	0	0	—	—	2	2	4	50.0%	1	0	1	100.0%	3	2	5	60.0%
2017	19	0	1	1	0.0%	1	3	4	25.0%	1	1	2	50.0%	0	3	3	0.0%	2	8	10	20.0%
2018	20	0	0	—	—	0	0	—	—	0	1	1	0.0%	0	0	—	—	0	1	1	0.0%
2020	22	0	0	—	—	0	0	—	—	0	1	1	0.0%	0	0	—	—	0	1	1	0.0%
2021	23	0	0	—	—	0	0	—	—	0	1	1	0.0%	0	0	—	—	0	1	1	0.0%
2022	24	0	3	3	0.0%	0	1	1	0.0%	3	4	7	42.9%	1	0	1	100.0%	4	8	12	33.3%
Career		0	4	4	0.0%	1	4	5	20.0%	6	12	18	33.3%	2	5	7	28.6%	9	25	34	26.5%

Opponent ranking data available for 34/35 (97.1%) of Stefan Kozlov's ATP main draw matches.

Performance Stats

Stefan Kozlov performance statistics by season
Season	Age	Sample	Aces/M	DFs/M	1st Sv%	1st Sv Pts%	2nd Sv Pts%	BP Saved%	BP Conv%	Svc Pts%	Ret Pts%
2013	15	1/1	4.0	3.0	43.5%	74.5%	42.6%	62.5%	44.4%	56.5%	36.0%
2014	16	1/1	2.0	4.0	56.4%	61.3%	50.0%	63.6%	16.7%	56.4%	35.5%
2015	17	2/2	0.5	3.0	44.3%	48.1%	35.6%	27.8%	67.5%	41.3%	42.2%
2016	18	5/5	4.2	4.8	55.8%	67.8%	41.9%	67.2%	40.4%	56.9%	38.4%
2017	19	11/11	3.6	4.1	58.0%	65.2%	44.1%	53.2%	35.0%	56.5%	32.9%
2018	20	1/1	2.0	5.0	50.9%	65.5%	35.7%	20.0%	50.0%	50.9%	28.0%
2020	22	1/1	1.0	5.0	68.5%	54.1%	57.1%	36.4%	50.0%	55.1%	31.7%
2021	23	1/1	1.0	1.0	76.4%	54.8%	61.5%	42.9%	25.0%	56.4%	32.7%
2022	24	12/12	1.6	4.8	72.4%	60.0%	43.6%	59.6%	35.7%	55.2%	36.0%
Career		35/35	2.6	4.3	62.0%	62.4%	43.9%	54.8%	38.2%	55.1%	35.3%

Advanced Stats

Stefan Kozlov advanced statistics by season
Season	Age	Elo	P+	Serve+	Return+	PD	TPW%	Hard Elo	Clay Elo	Grass Elo	Set Win %	Set Margin	Dec. Set	Tiebreak	Pressure+	Schedule
2013	15	1490	100.2	-4.35	+1.56	0.828	46.1%	—	—	—	33.3%	-1.33	0–1	1–0	—	+0.13
2014	16	1454	100.0	+0.67	0.00	0.813	45.3%	—	—	—	0.0%	-3.00	—	—	—	-0.04
2015	17	1420	101.3	-5.76	-0.97	0.718	41.8%	—	—	—	0.0%	-3.50	—	—	—	+0.21
2016	18	1481	107.5	-3.43	+1.33	0.891	48.1%	—	—	+119	54.5%	+0.09	1–0	—	—	-0.03
2017	19	1550	118.7	-5.47	-0.25	0.757	44.9%	-74	—	+123	21.7%	-1.70	2–1 (67%)	0–3 (0%)	100.1	+0.21
2018	20	1528	106.2	+0.19	-0.20	0.570	40.2%	—	—	—	0.0%	-3.50	—	—	—	-0.08
2019	21	1514	100.9	—	—	—	—	—	—	—	—	—	—	—	—	—
2020	22	1514	104.1	-1.24	+2.90	0.705	43.9%	—	—	—	33.3%	-2.33	0–1	1–0	—	-0.06
2021	23	1550	110.6	+2.69	+0.42	0.749	44.9%	—	—	—	0.0%	-3.00	—	—	—	+0.04
2022	24	1530	118.4	-4.38	+0.86	0.803	45.9%	+20	—	—	32.3%	-1.48	2–0	1–1	—	-0.54
2023	25	1458	91.9	—	—	—	—	—	—	—	—	—	—	—	—	—
2024	26	1433	92.7	—	—	—	—	—	—	—	—	—	—	—	—	—
2025	27	1436	101.4	—	—	—	—	—	—	—	—	—	—	—	—	—
2026	28	1418	97.5	—	—	—	—	—	—	—	—	—	—	—	—	—
Career		1674	113.0	-4.10	+0.48	0.784	45.4%	-15	—	+121	28.4%	-1.58	5–3 (63%)	3–4 (43%)	104.8	-0.46

Tournament Results by Category

Grand Slams

Stefan Kozlov Grand Slams results by season
Season	Age	AO	RG	W	USO	W-L Win %
2014	16	—	—	—	Q2	1–1 (50%)
2015	17	—	—	—	Q1	0–1 (0%)
2016	18	—	Q1	Q1	Q1	0–3 (0%)
2017	19	Q1	Q2	Q2	Q1	2–4 (33%)
2018	20	Q3	Q1	Q2	—	3–3 (50%)
2019	21	—	—	—	Q1	0–1 (0%)
2021	23	—	—	—	Q1	0–1 (0%)
2022	24	R64	Q1	R128	R128	3–5 (38%)
2023	25	Q1	—	—	—	0–1 (0%)
W-L		3–4 (43%)	1–4 (20%)	4–5 (44%)	1–7 (12%)	9–20 (31%)

Masters 1000

Stefan Kozlov Masters 1000 results by season
Season	Age	CIN	IW	MIA	W-L Win %
2014	16	—	Q1	—	0–1 (0%)
2015	17	Q1	—	—	0–1 (0%)
2016	18	Q2	—	—	1–1 (50%)
2017	19	R64	R128	Q2	1–3 (25%)
2018	20	—	Q1	Q1	0–2 (0%)
2021	23	—	Q2	—	1–1 (50%)
2022	24	Q1	Q2	Q1	1–3 (25%)
2023	25	—	Q1	—	0–1 (0%)
W-L		1–4 (20%)	2–6 (25%)	1–3 (25%)	4–13 (24%)

ATP 500

Stefan Kozlov ATP 500 results by season
Season	Age	MEX	QUE	WAS	WAS	VAL	W-L Win %
2014	16	—	—	Q1	—	R32	0–2 (0%)
2016	18	—	Q1	—	—	—	0–1 (0%)
2017	19	R32	R16	R64	—	—	5–3 (62%)
2018	20	—	—	Q1	—	—	0–1 (0%)
2021	23	R32	—	—	—	—	3–1 (75%)
2022	24	R16	Q1	R64	—	—	2–4 (33%)
2025	27	Q2	—	—	—	—	1–1 (50%)
2026	28	Q1	—	—	Q1	—	0–2 (0%)
W-L		8–6 (57%)	3–3 (50%)	0–4 (0%)	0–1 (0%)	0–1 (0%)	11–15 (42%)

ATP 250

Stefan Kozlov ATP 250 results by season
Season	Age	ATL	BRI	DAL	DLB	LIB	U.S	NWP	SDG	WSA	MEM	SYD	W-L Win %
2013	15	—	—	—	—	—	—	R32	—	—	—	—	0–1 (0%)
2014	16	—	—	—	Q1	—	—	—	—	—	—	—	0–1 (0%)
2015	17	—	—	—	R32	—	—	—	—	—	R32	—	0–2 (0%)
2016	18	—	—	—	—	QF	—	R16	—	—	—	—	3–2 (60%)
2017	19	R32	Q1	—	R32	R16	—	R32	—	—	—	—	3–5 (38%)
2018	20	—	—	—	Q1	—	R32	—	—	—	—	—	2–2 (50%)
2020	22	—	—	—	R32	—	—	—	—	—	—	—	1–2 (33%)
2021	23	—	—	—	Q2	—	—	—	—	—	—	—	1–1 (50%)
2022	24	Q1	—	—	QF	Q1	—	R32	R32	—	—	Q1	4–6 (40%)
2023	25	—	—	Q2	Q1	—	—	—	—	Q1	—	—	1–3 (25%)
2024	26	—	—	—	Q1	—	Q1	—	—	—	—	—	0–2 (0%)
2025	27	—	—	—	Q1	—	—	—	—	—	—	—	0–1 (0%)
W-L		2–2 (50%)	0–1 (0%)	1–1 (50%)	6–11 (35%)	3–3 (50%)	2–2 (50%)	1–4 (20%)	0–1 (0%)	0–1 (0%)	0–1 (0%)	0–1 (0%)	15–28 (35%)

Results show the best round reached per tournament and season.

ATP Ranking History full ranking history →

Career high

103

Career-high date

Jul 18, 2022

First Top 100

—

First Top 50

—

First Top 20

—

First Top 10

—

Ranking History Matrix

Stefan Kozlov ranking history by month and season
Season	Age	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
2013	15	1394	1413	1425	1417	1451	1466	1491	—	—	1292	1084	1083
2014	16	1080	1080	1051	870	855	851	857	851	763	444	467	467
2015	17	455	410	417	431	373	365	356	369	368	494	353	351
2016	18	316	337	289	206	213	176	159	154	152	144	116	116
2017	19	122	115	122	147	144	126	132	141	144	135	167	167
2018	20	155	160	167	175	176	246	254	251	249	352	414	316
2019	21	336	327	339	366	406	405	403	549	550	485	420	422
2020	22	368	374	386	—	—	—	—	387	393	379	369	371
2021	23	375	385	345	363	366	347	322	312	251	247	159	159
2022	24	151	122	120	122	113	107	113	111	127	132	201	198
2023	25	239	354	371	368	363	387	389	396	441	655	779	787
2024	26	722	816	653	451	454	442	367	349	350	340	352	354
2025	27	354	359	404	488	375	367	431	450	448	469	304	289
2026	28	285	259	260	256	292	317	292	297	—	—	—	—

Similar Players

Other ATP players with comparable peak level, era, career record, and career scale.

Stefan Kozlov's most statistically similar ATP players
Player	Country	Peak Rank	Peak Elo	M	W	L	Win %	Years	Match Log
Pedro Sousa	POR	99	1,567	37	9	28	24.3%	2007–2023	Match log
Luca Vanni	ITA	100	1,672	23	5	18	21.7%	2015–2019	Match log
Elias Ymer	SWE	105	1,696	97	29	68	29.9%	2013–2026	Match log
Emilio Gomez	ECU	90	1,630	26	7	19	26.9%	2013–2023	Match log
Austin Krajicek	USA	94	1,713	37	12	25	32.4%	2008–2025	Match log
Darian King	BAR	106	1,699	13	3	10	23.1%	2015–2023	Match log
Noah Rubin	USA	125	1,693	29	8	21	27.6%	2014–2021	Match log
John-Patrick Smith	AUS	108	1,687	27	5	22	18.5%	2013–2021	Match log
Antoine Hoang	FRA	98	1,641	19	6	13	31.6%	2019–2021	Match log
Brayden Schnur	CAN	92	1,642	19	4	15	21.1%	2014–2021	Match log
Yannick Maden	GER	96	1,743	26	9	17	34.6%	2016–2020	Match log
Bjorn Fratangelo	USA	99	1,740	62	22	40	35.5%	2015–2023	Match log

Frequently Asked Questions

How old is Stefan Kozlov?: Stefan Kozlov is 28 years old, born on February 1, 1998.
Which country does Stefan Kozlov represent?: Stefan Kozlov represents United States in TennisDB's ATP records.
How tall is Stefan Kozlov?: Stefan Kozlov is 183 cm / 6'0".
Is Stefan Kozlov left-handed or right-handed?: Stefan Kozlov plays right-handed.
How many Grand Slams has Stefan Kozlov won?: Stefan Kozlov has not won a Grand Slam title.
How many Masters 1000 titles has Stefan Kozlov won?: TennisDB does not group any of Stefan Kozlov's titles under the modern Masters 1000 category.
What is Stefan Kozlov's highest ATP ranking?: Stefan Kozlov's career-high ATP singles ranking is world No. 103, first achieved on July 18, 2022.
What is Stefan Kozlov's career win-loss record?: Stefan Kozlov has a career ATP singles record of 9 wins and 26 losses (25.7%).
How much career prize money has Stefan Kozlov earned?: Stefan Kozlov has earned at least $1,131,991 in career prize money from professional tennis.
What turned-professional year does TennisDB record for Stefan Kozlov?: TennisDB records 2013 as Stefan Kozlov's turned-professional year.
Which seasons of Stefan Kozlov's career appear in TennisDB?: Stefan Kozlov appears in TennisDB's ATP main-tour match records from 2013 through 2022.
On which surface does Stefan Kozlov have the highest recorded win rate?: Among surfaces with at least 20 recorded matches, Stefan Kozlov's highest ATP main-draw win rate is on hard: 19.0% (4–17).
Who has Stefan Kozlov faced most often?: Stefan Kozlov's most frequent opponent is Steve Johnson, with a head-to-head record of 3–2 across 5 meetings.