Andre Agassi admits he’d struggle to crack the world’s top five in the new power era of men’s tennis – but has no doubt his legendary wife could challenge for women’s grand slam spoils if fit and healthy.

Kimiko Date-Krumm’s inspired run to the third round of the Australian Open at 42 years of age impressed Agassi and prompted an inevitable question.

Could 43-year-old Steffi Graf, a 22-times grand slam champion and former world No.1, compete with the likes of Serena Williams and reigning rankings queen Victoria Azarenka if she too made a comeback?

Chronic knee and calf injuries aside, Agassi was certain she could.

“From a health perspective, it would be impossible,” Agassi told AAP during his promotional visit to Australia at the weekend.

“You’ve got to be healthy. I don’t know how Kimiko 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.”

Agassi, himself a former world No.1 and eight-times major winner, said he was amazed “watching the standard continually sort of get better.”.

“You wonder how it’s possible to continue at that sort of rate,” he said.

“What Federer did when he came and, when I said goodbye, a lot had to do with what I knew was untouchable.

“It’s just a different standard of tennis. It’s a different rules of engagement when guys can do what these guys can do.

“I don’t recognise it from a standpoint of strategy because I counted on getting somebody behind in a point and then slowly smothering them.

“But nobody’s behind in a point. You never know when they’re behind in a point. That would have eliminated any ability I had to move forward in the court.

“Means I would have had to be a different player, would’ve had to have a different body. It means the game has gotten a lot better.”