2020: ATP debut He made his ATP main draw debut at the
2020 Erste Bank Open in the singles draw as lucky loser, where he was defeated by
Dominic Thiem, 4–6, 5–7.
2021: Challenger Tour success, Top 250 debut In March, ranked No. 389 in the world, he made it to the final of the Challenger Tour event in Lugano, Switzerland, where he lost to
Dominic Stephan Stricker. In July, he made another Challenger final in Perugia, Italy losing to
Tomas Martin Etcheverry in singles. At the same tournament, he took his revenge, winning his third Challenger doubles title for 2021 by defeating the Argentinian pair Tomas Etcheverry/Renzo Olivo, partnering Dominic Stricker. As a result, he reached a career-high ranking of No. 269 in singles and No. 220 in doubles on 12 July 2021.
2022-2024: First Challenger title, top 200 Ranked No. 265, in July, he qualified for his second ATP singles main draw at the
2022 Generali Open Kitzbühel as a lucky loser where he lost to
Dusan Lajovic. Ranked No. 286, in May, he qualified for the
2023 Geneva Open but lost to
Bernabe Zapata Miralles. He won his first singles Challenger at the
2023 Bratislava Open defeating
Dimitar Kuzmanov. As a result he moved close to 80 positions into the top 200 at world No. 187 on 19 June 2023. Ranked No. 166, he also qualified for the
2023 Sofia Open but lost to
Sebastian Ofner.
2025: First ATP wins and semifinal At the
2025 Moselle Open, as a lucky loser, he recorded his first match wins at the tour-level to reach his first ATP Tour quarterfinal, defeating third seed
Alexander Bublik in the round of 16. As a result he moved back up 36 spots to world No. 186 in the ATP singles rankings and became the first Ukrainian to reach a tour-level quarterfinal since
Sergiy Stakhovsky in
2019 Marseille, who also reached the last eight as a lucky loser. Sashko reached his first ATP semifinal getting his revenge over qualifier
Clément Tabur, having previously lost to him in the last qualifying round. ==ATP Challenger Tour finals==