| Challenger Charlottesville | 11/01 21:50 | 25 | [199] Mitchell Krueger v Stefan Kozlov [132] | 5-7,6-0,6-7 | |
| Challenger Las Vegas | 10/30 19:00 | 29 | [444] Tennys Sandgren v Stefan Kozlov [133] | 7-5,6-3 | |
| Challenger Las Vegas | 10/29 19:55 | 28 | [133] Stefan Kozlov v Steve Johnson [119] | 6-3,1-6,7-5 | |
| Challenger Las Vegas | 10/28 19:10 | 27 | [225] Alexis Galarneau v Stefan Kozlov [133] | 7-6,4-6,3-6 | |
| Challenger Las Vegas | 10/27 18:00 | 26 | [321] Evan Zhu v Stefan Kozlov [133] | 6-7,2-6 | |
| Challenger Las Vegas | 10/25 19:40 | 25 | Cannon Kingsley v Stefan Kozlov | 5-7,6-4,1-6 | |
| Challenger Fairfield | 10/11 18:20 | 25 | Sam Riffice v Stefan Kozlov | 3-6,6-2,6-3 | |
| Challenger Tiburon | 10/06 19:35 | 26 | [243] Alexis Galarneau v Stefan Kozlov [130] | 6-1,7-5 | |
| Challenger Tiburon | 10/04 19:45 | 25 | [361] Giovanni Oradini v Stefan Kozlov [130] | 1-6,4-6 | |
| Challenger Charleston | 09/27 14:00 | 25 | Evan Zhu v Stefan Kozlov | Cancelled | |
| ATP San Diego | 09/20 00:30 | 25 | [73] Jeffrey John Wolf v Stefan Kozlov [108] | 6-2,7-6 | |
| Challenger Cary | 09/15 20:00 | 26 | [307] Yasutaka Uchiyama v Stefan Kozlov [110] | Retired | |
| Challenger Cary | 09/13 18:00 | 25 | Cannon Kingsley v Stefan Kozlov | 6-2,2-6,2-6 | |
| US Open | 08/29 16:00 | 23 | [1] Daniil Medvedev v Stefan Kozlov [111] | 6-2,6-4,6-0 | |
| Challenger Granby | 08/23 14:00 | 25 | Stefan Kozlov v Aidan Mchugh | Cancelled | |
| ATP Cincinnati | 08/13 20:15 | 14 | [113] Stefan Kozlov v Dusan Lajovic [68] | 3-6,5-7 | |
| Challenger Chicago | 08/10 18:50 | 25 | [113] Stefan Kozlov v Ernesto Escobedo [174] | 4-6,6-7 | |
| ATP Washington | 08/01 21:20 | 24 | [111] Stefan Kozlov v Jack Draper [81] | 5-7,2-6 | |
| ATP Atlanta | 07/23 18:00 | 26 | [196] Ramkumar Ramanathan v Stefan Kozlov [103] | 6-0,6-1 | |
| Challenger Indianapolis | 07/18 22:45 | 25 | [269] Aleksandar Kovacevic v Stefan Kozlov [103] | 6-3,6-7,6-4 | |
| ATP Newport | 07/11 18:40 | 25 | [104] Stefan Kozlov v Steve Johnson [95] | 5-7,3-6 | |
| Wimbledon | 06/28 15:40 | 23 | [107] Stefan Kozlov v Diego Schwartzman [15] | 3-6,2-6,2-6 | |
| Wimbledon | 06/23 10:00 | 19 | [107] Stefan Kozlov v Dennis Novak [155] | 5-7,4-6,7-5,6-3,3-6 | |
| Wimbledon | 06/22 10:00 | 19 | [107] Stefan Kozlov v Dominic Stephan Stricker [188] | 7-6,4-6,6-3 | |
| Wimbledon | 06/20 12:15 | 14 | [107] Stefan Kozlov v Evan Furness [229] | 7-5,6-3 | |
| ATP Queens | 06/11 11:20 | 26 | [111] Stefan Kozlov v Steve Johnson [87] | 0-6,0-6 | |
| ATP Hertogenbosch | 06/04 11:00 | 14 | [112] Stefan Kozlov v Matthew Ebden [395] | 4-6,4-6 | |
| Challenger Surbiton | 06/02 10:00 | 26 | [112] Stefan Kozlov v Brandon Nakashima [75] | 4-6,3-6 | |
| Challenger Surbiton | 05/30 16:10 | 25 | [113] Stefan Kozlov v Mats Moraing [116] | 6-3,7-6 | |
| French Open | 05/17 16:00 | 14 | [116] Stefan Kozlov v Nino Serdarusic [188] | 5-7,0-6 |
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.