ROCKVILLE, Md. -- Mike Tyson is challenging a $10 million divorce settlement with his second wife.

Monica Turner Tyson, a pediatric resident at Georgetown University Medical Center, sued her husband for divorce in January, accusing the former heavyweight boxing champion of adultery.

A week after Tyson lost to Lennox Lewis in June, she filed to stop her husband from spending his fight earnings, according to documents unsealed recently in Montgomery County Circuit Court.

The couple drafted a settlement under which Tyson would pay his wife an additional $10 million from the fight and two later matches. She would also remain in the $4 million Bethesda mansion where she is raising the couple's two children, Rayna, 6, and Amir, 5.

Tyson, however, did not pay $4 million of the first $5 million owed by July 31. After Turner tried to enforce the payment schedule in September, Tyson's attorneys challenged the agreement, according to the court filings.

"There are questions as to whether the paper is an enforceable contract," said Tyson's attorney, Patrick Dragga.

Turner's attorney disagrees.

"It's Dr. Turner's conviction that she and her husband have come to a resolution of their economic differences through this agreement, which was initiated by Mike Tyson," Sanford Ain said. "She'd like him to honor the agreement."

Tyson's attorneys said the July 18 settlement was invalid in part because it was drawn by Turner's brother, Michael S. Steele, a lawyer who is currently the Republican candidate for lieutenant governor in Maryland.

A two-day hearing on the settlement is set for Dec. 16.