Top American players John Isner and Ryan Harrison have hired new coaches for the upcoming ATP World Tour season.

Isner announced on Monday that he will be teaming up with former player and current tennis commentator and ATP Board member Justin Gimelstob as his new coach for the coming season.

“I’m really excited to start working with Justin,” Isner told ATPWorldTour.com. “He has so much experience within the tennis business and I’ve long respected his knowledge of the sport. I think it will be great for me to have a new perspective helping me with my game.”

Isner had a mediocre year on the tour by relative standards. Although he finished as the top ranked American, he was at the tail end of the Top 20. He did manage to win two titles and reach the semi-finals of the Indian Wells Masters event.

“I had a great run with Mike [Sell] and feel I really learned a lot from him throughout the course of our coaching relationship. I just thought it was time to try something new, and with Justin I believe I will have a strong and passionate new voice on my team. In spending some time with Justin throughout the fall I have full confidence that he has a clear vision for my game and an understanding of what I need to do in order to play my best tennis.”

Gimelstob revealed that he will continue to undertake his duties as a commentator and a board member.

“John is a very unique talent, a great guy both on and off the court and I am thrilled to be able to be a part of his team,” Gimelstob said. “Coaching is in my blood. I have the highest regard for the level of commitment coaching a player of John’s pedigree entails.

World No. 190 Harrison hired Grant Doyle as his coach after parting ways with him in 2012. With Doyle, Harrison reached a career-high No. 43 on the tour and will be looking to achieve similar success this time around as well.