Tennis's first couple were scheduled to play mixed doubles at last year's French Open after Agassi bet his wife he would win the 2003 Australian Open title, which he did. But their plans were scuppered when Graf became pregnant.

"I sort of jumped the gun last year," Agassi said after winning through to the semi-finals at Melbourne Park on Tuesday with a 6-2, 2-0 victory over Frenchman Sebastien Grosjean, who retired injured.

"But I guess she still owes us one. I won the bet here last year, so it didn't make much sense to do it in Paris. Maybe we'll do it back here."

Last year, the 33-year-old American famously promised that he and Graf would play their own version of 'Mr and Mrs' in Paris.

But Graf, now 34, was unable to keep her end of the bargain as she was carrying their second child, daughter Jaz who was born in October.

The pair married in October 2001, the same month Graf gave birth to their son Jaden Gil.

Graf, who won 22 Grand Slam singles titles, retired from tennis in August 1999 and has not played since. She entered the mixed doubles at Wimbledon with John McEnroe in 1999, reaching the semi-finals.

A hen-pecked Agassi insisted, however, that he would be making no firm promises about next year without first consulting Graf.

"Listen, you can count on something: I'm not going to say anything that's going to get any sideways looks when I walk through the front door," joked Agassi.

"Steffi can say more without saying anything. It's just a great ability to have. If I could imitate that look, I'd have it on the tennis court."