Chicago Bears wide receiver Brandon Marshall challenged a Detroit Lions fan Thursday on Twitter with a $25,000 offer to go into the ring with him.

Marshall exchanged in a series of tweets after the fan brought up Marshall’s statement last year calling the Lions a little brother of the Bears.

The Lions fan also insulted the receiver’s mother with one of his tweets.

Marshall’s first Twitter challenge to the fan was to step into the ring with him for $5,000. Then he said that if he lost he would give the fan an additional $10,000, but if Marshall won, the fan would have to perform 100 hours of community service at an orphanage.

The Lions fan responded by asked for $25,000 to fight in Detroit. Marshall agreed to do so but wanted an apology to his mother.

The fan offered no reply for a while before tweeting that he would fight only if the Bears (3-6) won three more games this season. At that point, the Lions backer went private with his Twitter account.

Marshall told ESPN.com that the money would go to charity.

The Lions lead the NFC North with a 7-2 record and the Bears are in last place in the division.