"Caron Butler underwent surgery on his right knee Tuesday morning, according to a source, but the Dallas Mavericks will not comment on the severity of the injury until later in the day.

Butler injured the knee early in Saturday's game at Milwaukee. On Sunday a source said that the initial diagnosis was that Butler had at least a partial tear of the patellar tendon, an injury that could keep the Mavs' starting small forward out for a couple of months.

The franchise was holding its breath that it was not a full tear of the tendon which could end Butler's season.

After Tuesday morning's shootaround in preparation for that night's home game against the Portland Trail Blazers -- in which Dallas will also be without Dirk Nowitzki (sprained right knee) for a fifth consecutive game -- Mavs coach Rick Carlisle would not address Butler's situation, only to say that the team would make an official comment Tuesday afternoon."