Bajin had a brief career on the
Association of Tennis Professionals (ATP) Tour, reaching career high rankings of 1,149 in singles and 1,180 in doubles. Bajin is best known as the former hitting partner of
Serena Williams when she won 13 of her Grand Slam titles. Later on, he was a hitting partner for
Victoria Azarenka,
Sloane Stephens, and
Caroline Wozniacki. He coached
Naomi Osaka to two Grand Slam titles, one at the
2018 US Open and one at the
2019 Australian Open. He won the inaugural
WTA Coach of the Year award in 2018 for coaching Osaka to her first two titles, the US Open and the
Indian Wells Open. Osaka split with Bajin shortly after her Australian Open title. In April 2019, Bajin began working with
Kristina Mladenovic. He split with Mladenovic in October 2019 and started coaching
Dayana Yastremska. In September 2020 they split after Yastremska had a disappointing performance in the
2020 US Open. From November 2020 to July 2022, Bajin coached
Karolína Plíšková. She reached the
2021 Wimbledon Championships final under his tutelage. The two reunited in December 2022 for the 2023 season. He briefly coached
Alycia Parks in the beginning of 2024 during the Sunshine double. In December 2024,
Donna Vekić announced she had hired Bajin as her new coach replacing Nikola Horvat who had quit the previous month for family reasons. In August 2025, Bajin began working
Diana Shnaider ahead of the Cincinnati Open, following her split from her previous coaches
Dinara Safina and Carlos Martinez. The collaboration immediately showed results, with Shnaider winning her first WTA title of 2025 in Monterrey, shortly after the partnership started. ==References==