World number six Karolina Pliskova said on Friday she had hired Sascha Bajin as her new coach for the 2021 season.
Pliskova published a photo on Facebook and Twitter featuring Bajin, fitness coach Azuz Simchich and a caption saying "Team Pliskova 2021".
The 36-year-old German, Bajin led Naomi Osaka to back-to-back Grand Slam wins at the US Open in 2018 and the Australian Open in 2019.
The 2018 WTA Coach of the Year has also worked with Serena Williams, Kristina Mladenovic and Dayana Yastremska.
Pliskova, the 2016 US Open finalist and former world number one, announced she had parted ways with coach Dani Valverdu, hired for 2020, earlier this month.
The 28-year-old Czech won her first tournament of the year in Brisbane and reached the final in Rome in September, but she failed to get beyond the round of 32 at the season's three Grand Slams.