Martina Navratilova turned her tennis skills to coaching after winning a record 59 grand slam titles during a glittering playing career.
She followed the likes of Boris Becker, who helped Novak Djokovic win at Wimbledon in July 2014. The pair have been working together since December 2013.
The German is one of several former grand slam champions to recently take up a coaching role with a top player.
The pairing of 17-time grand slam champion Roger Federer and Stefan Edberg seemed obvious. The Swede, a six-time grand slam winner himself, was a player Federer idolized when he was growing up. Both men are renowned for being extremely stylish players.
Eight-time grand slam champion Ivan Lendl helped Andy Murray to win his first two major titles, as well as an Olympic gold medal.
Since splitting with Lendl in March 2014, Murray has teamed up with former women's No. 1 Amelie Mauresmo.
Former Wimbledon champion Goran Ivanisevic (left) is something of a veteran on the coaching circuit having started coaching fellow Croatian Marin Cilic in 2010.
Cilic won his first grand slam title at the 2014 U.S. Open, beating another final debutant Kei Nishikori.
Michael Chang (right), who stunned Edberg in the 1989 French Open final as a teenager, took up a coaching role with rising Japanese star Nishikori in December 2013.
Nishikori made it to the semifinals of the season-ending ATP World Tour Finals in 2014, and reached a career-high fourth in the rankings the following March.
Navratilova, who holds the Open Era record for total singles and doubles titles in the men's and women's game, did not have the same success with Agnieszka Radwanska.
The Pole, still seeking her first grand slam title, had dropped to ninth in the rankings when they split after only a few months together in April 2015.