| Challenger Orlando | 01/02 20:20 | 25 | [316] Stefan Kozlov v Mitchell Krueger [228] | 6-2,5-7,6-3 | |
| Challenger Orlando | 12/31 19:00 | - | [312] Alejandro Gonzalez v Stefan Kozlov [316] | Cancelled | |
| Challenger Houston | 11/13 17:35 | 25 | [115] Paolo Lorenzi v Stefan Kozlov [414] | 6-4,3-6,6-4 | |
| Challenger Knoxville | 11/04 16:55 | 45 | [391] Evan Song v Stefan Kozlov [352] | 6-4,3-6,6-3 | |
| Challenger Charlottesville | 10/28 16:00 | 46 | [470] Petros Chrysochos v Stefan Kozlov [348] | 1-6,6-3,6-2 | |
| Challenger Charlottesville | 10/27 16:10 | 45 | Emil Reinberg v Stefan Kozlov | 6-3,6-7,1-6 | |
| Challenger Las Vegas | 10/23 18:00 | 25 | [194] Kamil Majchrzak v Stefan Kozlov [348] | 6-0,6-2 | |
| Challenger Calgary | 10/15 20:30 | 25 | [262] Stefan Kozlov v Jan Choinski [267] | 3-6,3-6 | |
| Challenger Monterrey | 10/01 21:25 | 25 | Stefan Kozlov v Lucas Gomez | 2-6,4-6 | |
| Challenger Aptos | 08/06 18:00 | 25 | [252] Stefan Kozlov v Kaichi Uchida [296] | 4-6,1-6 | |
| ATP Washington Qual | 07/28 14:00 | 45 | [427] Jared Hiltzik v Stefan Kozlov [243] | 6-3,6-3 | |
| Wimbledon Qual | 06/26 14:50 | 45 | [246] Stefan Kozlov v Yannick Maden [134] | 1-6,3-6 | |
| Wimbledon Qual | 06/25 14:05 | 44 | [175] Dustin Brown v Stefan Kozlov [199] | 3-6,1-6 | |
| Challenger Ilkley Qual | 06/17 11:35 | 45 | [468] Brydan Klein v Stefan Kozlov [182] | 4-6,6-1,7-5 | |
| Challenger Nottingham | 06/12 10:00 | 25 | [182] Stefan Kozlov v Christopher Eubanks [190] | 3-6,3-6 | |
| Challenger Nottingham | 06/12 10:00 | - | Stefan Kozlov v James Duckworth | Cancelled | |
| Challenger Surbiton Qual | 06/02 13:55 | 45 | Stefan Kozlov v Daniel Evans | 1-6,0-6 | |
| Challenger Vicenza Qual | 05/27 10:50 | 46 | [175] Stefan Kozlov v Martin Cuevas [296] | 4-6,1-6 | |
| Challenger Vicenza Qual | 05/26 11:50 | 45 | Stefan Kozlov v Edoardo Sardella | 6-1,6-2 | |
| French Open Qual | 05/22 08:00 | 44 | [175] Stefan Kozlov v Yasutaka Uchiyama [234] | 4-6,5-7 | |
| Challenger Bordeaux | 05/18 09:30 | 27 | [206] Reilly Opelka v Stefan Kozlov [189] | 7-6,6-1 | |
| Challenger Bordeaux | 05/16 09:55 | 26 | [233] Antoine Hoang v Stefan Kozlov [189] | 3-6,6-7 | |
| Challenger Bordeaux | 05/15 13:05 | 25 | [189] Stefan Kozlov v Pierre-Hugues Herbert [90] | 6-2,7-6 | |
| Challenger Aix en Provence | 05/08 15:05 | 25 | Stefan Kozlov v Constant Lestienne | 6-7,4-6 | |
| Challenger Sarasota | 04/20 20:30 | 27 | [231] Hugo Dellien v Stefan Kozlov [170] | 5-7,6-1,7-6 | |
| Challenger Sarasota | 04/18 20:30 | 26 | [170] Stefan Kozlov v Donald Young [131] | 6-4,6-4 | |
| Challenger Sarasota | 04/16 18:00 | 25 | [219] Mitchell Krueger v Stefan Kozlov [170] | 4-6,3-6 | |
| ATP Houston | 04/10 21:35 | 25 | [184] Stefan Kozlov v Guido Pella [63] | 3-6,2-6 | |
| ATP Houston Qual | 04/08 18:20 | - | [182] Stefan Kozlov v Akira Santillan [170] | 6-2,6-0 | |
| ATP Houston Qual | 04/07 21:25 | 26 | [145] Thomaz Bellucci v Stefan Kozlov [182] | 7-6,3-6,6-7 |
Wikipedia - Stefan Kozlov
Stefan Kozlov (Russian: Стефан Козлов, STEF-ahn KOZ-lov; born February 1, 1998) is an American professional tennis player of Russian descent. He has a career-high ATP ranking of world No. 103 achieved on 18 July 2022 and doubles ranking of world No. 180 on 19 June 2017.
Kozlov made his ATP World Tour debut as a wildcard in 2013 Hall of Fame Tennis Championships at the age of 15. He reached two junior Grand Slam finals in 2014 and finished the year at World No. 3 in the ITF Junior Combined rankings.