ROCKVILLE, Md. -- Mike Tyson's second wife has filed for divorce, accusing the former heavyweight boxing champion of adultery.

Monica Tyson seeks an unspecified "reasonable sum," according to divorce papers filed Thursday in Montgomery County Circuit Court.

Mike Tyson countered Thursday by suing for divorce in Las Vegas, claiming incompatibility, spokesman Scott Miranda said. There was a divorce case filed under the name Michael Tyson in Las Vegas, and it was ordered sealed.

"This is a private situation," the boxer said Friday in a statement. "It will not be a distraction. I'm 100 percent focused on knocking out Lennox Lewis."

A press conference was called for Tuesday to announce details of a Tyson-Lewis fight, expected to be in April.

Monica Tyson also wants legal custody of their two children -- Rayna, 5, and Amir, 4 -- and, according to the filing, the fighter has agreed to that.

"The defendant committed adultery during the marriage, and such adultery has neither been forgiven nor condoned by the plaintiff," her filing said.

Monica Tyson, a second-year resident in pediatrics at Georgetown University Medical Center, also asked the court to equally distribute their marital property.

The divorce complaint said her contribution to the family's finances has been considerable, while the "defendant's negative, non-monetary contributions have been substantial."

The boxer met his second wife while he was serving a rape sentence in an Indiana prison. They were married in April 1997, in Bethesda, where Monica Tyson lives with her two children.

The boxer previously was married for a year to actress Robin Givens. That marriage ended in divorce in 1989.

Shelly Finkel, Tyson's adviser, was traveling Friday and not available for comment.

Monica Tyson is being represented by attorney Sanford Ain, who also represented Frances Hughes Glendening in her divorce from Gov. Parris Glendening.

Ain said he was hopeful the two sides would be able to work out an agreement without going to trial, but would not say what his client was seeking.