Mats Wilander, a seven-time Grand Slam champion who is now a TV commentator, is coaching Madison Keys on a trial basis.

"I'm not Madison Keys’ full-time coach," Wilander told L'Equipe. "I was contacted by [USTA general manager of player development] Martin Blackman to work with a player or group of players. We agreed on Madison."

The two trained before Indian Wells, and Miami will be their first tournament working together. The 21-year-old American was previously coached by Lindsay Davenport—with help from Davenport's husband, Jon Leach­—and another former pro, Lisa Raymond. She is now coached by the recently-retired Jesse Levine.

Wilander said he does not know what the length of the arrangement will be, but he plans to work with Keys at the Slams.

"I'd like to involve myself more, but I have quite a few obligations," he said.

Wilander added that he likes "the quality of her shots," but there was a lot of pressure on the up-and-coming Keys because of her obvious potential and the standard set by the Williams sisters.

"She's [in] the same position as Sloane Stephens,” he said. “To exist, she has to win Slams."

Keys, who a year ago reached a career-high of No. 16 and got to the semifinals of the Australian Open, has been hampered by injuries and is now No. 24 in the rankings.