Jack Sock, playing this week's ATP event in Washington, is now working with former USTA coach JayBerger.
"He's been in my corner for so many years now, and I just really like his energy," Sock told the ATP website.
Sock was previously coached by Troy Hahn, but he recently had a child and wants to spend more time at home.
Berger wants to build on Sock's offensive game and his variety on court.
"I think that he has some of the best weapons in the game in his serve, speed and forehand. We want to continue to work on his strengths and just add little parts to his game slowly," Berger told the ATP website.
The 24-year-old had a good run to start the season, but is coming off a knee injury during the grass-court events.
Sock is No. 19 in the rankings.
