Andre Agassi tells AAP that his wife, 43-year-old Steffi Graf, could be successful in today’s game. Graf, who retired in 1999, won 22 Grand Slams.

"From a health perspective, it would be impossible," Agassi said. "You've got to be healthy. I don't know how Kimiko [Date-Krumm] has done it. That's remarkable. From a game perspective, I can honestly say that—unlike in the men's game—Steffi's game from the mid-90s lives up to the standard of today. She can offset the power.

"The power of the women's game has changed considerably but she always had the ability to offset that by bringing people forward with her slice and keeping the ball down low. And she's such an athlete. I don't know if anyone has ever run like her in the history of the game. As a result, her best would match up, unlike mine. Mine would not. I'd work hard to be No. 5 in the world right now."