| Challenger Las Vegas | 10/17 18:00 | 26 | Stefan Kozlov v Alexander Ritschard | 5-7,6-4,6-1 | |
| Challenger Las Vegas | 10/15 20:55 | 25 | Blaz Rola v Stefan Kozlov | 4-6,3-6 | |
| Challenger Las Vegas | 10/14 23:15 | 24 | Stefan Kozlov v Evan Song | 6-4,6-3 | |
| US Open | 08/20 16:15 | 44 | Stefan Kozlov v Egor Gerasimov | 4-6,4-6 | |
| Challenger Binghamton | 07/23 20:45 | 24 | [274] Roberto Ortega-Olmedo v Stefan Kozlov [402] | Retired | |
| Challenger Winnetka | 07/11 19:15 | 26 | [406] Stefan Kozlov v Jason Kubler [188] | 2-6,3-6 | |
| Challenger Winnetka | 07/09 16:40 | 25 | [146] Adrian Menendez-Maceiras v Stefan Kozlov [406] | Retired | |
| Challenger Winnetka | 07/08 19:55 | 24 | [406] Stefan Kozlov v Evgeny Karlovskiy [216] | 6-2,6-4 | |
| Challenger Little Rock | 06/05 18:00 | 25 | [406] Stefan Kozlov v Zhe Li [239] | 3-6,7-5,0-6 | |
| Challenger Little Rock | 06/04 17:10 | 24 | Stefan Kozlov v Garrett Johns | 7-5,6-3 | |
| Challenger Savannah | 04/29 19:30 | 24 | [354] Aleksandar Vukic v Stefan Kozlov [366] | 6-2,7-6 | |
| Challenger Tallahassee | 04/24 23:40 | 25 | [374] Stefan Kozlov v Tennys Sandgren [103] | 3-6,2-6 | |
| Challenger Tallahassee | 04/22 15:30 | 24 | Stefan Kozlov v Alexander Zhurbin | 4-6,6-4,6-0 | |
| ITF M15 Sunrise | 04/11 17:30 | 26 | Stefan Kozlov v Dmitry Popko | 5-7,3-6 | |
| ITF M15 Sunrise | 04/10 18:50 | 25 | Stefan Kozlov v Mateus D C C Alves | 6-3,6-1 | |
| ITF M25 Calabasas | 03/24 20:00 | 29 | [492] Alexander Ritschard v Stefan Kozlov [339] | 6-2,0-6,7-6 | |
| ITF M25 Calabasas | 03/23 20:40 | 28 | Drew Baird v Stefan Kozlov | 2-6,2-6 | |
| ITF M25 Calabasas | 03/22 20:00 | 27 | Jonathan Gray v Stefan Kozlov | 2-6,1-6 | |
| ITF M25 Calabasas | 03/21 23:25 | 26 | Isaiah Strode v Stefan Kozlov | 6-7,0-6 | |
| ITF M25 Calabasas | 03/19 20:30 | 25 | [464] Ronnie Schneider v Stefan Kozlov [339] | 2-6,0-6 | |
| Challenger Drummondville | 03/11 14:35 | 24 | [435] Gijs Brouwer v Stefan Kozlov [340] | 7-5,6-3 | |
| Challenger Morelos | 02/21 17:00 | 26 | [338] Stefan Kozlov v Roberto Quiroz [182] | 4-6,6-7 | |
| Challenger Morelos | 02/19 20:35 | 25 | [310] Alexander Sarkissian v Stefan Kozlov [338] | Retired | |
| Challenger Morelos | 02/18 16:00 | 24 | [319] Evan Song v Stefan Kozlov [338] | 5-7,3-6 | |
| Challenger Dallas | 02/05 20:30 | 24 | [489] Alex Rybakov v Stefan Kozlov [333] | 6-2,6-1 | |
| Challenger Cleveland | 01/30 16:25 | 25 | [164] Brayden Schnur v Stefan Kozlov [336] | 7-6,6-4 | |
| Challenger Cleveland | 01/28 20:25 | 24 | [466] Louis Wessels v Stefan Kozlov [336] | 4-6,7-5,5-7 | |
| Challenger Newport Beach | 01/21 18:00 | 166 | [311] Stefan Kozlov v Maxime Cressy [335] | 5-7,1-6 | |
| Challenger Columbus | 01/07 19:00 | 24 | [366] Jeffrey John Wolf v Stefan Kozlov [309] | 6-2,7-6 | |
| Challenger Orlando | 01/03 19:20 | 26 | [264] Nino Serdarusic v Stefan Kozlov [316] | 6-2,7-5 |
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.