MILWAUKEE -- Dallas forward Caron Butler left the Mavericks' game against Milwaukee in the first quarter Saturday night after injuring his right knee.
The extent of Caron's injury wasn't known after Dallas' 99-87 loss, but the Mavericks were preparing to play an extended time without the 6-foot-7 forward who entered the night averaging 15.4 points.
"We're afraid that it's potentially serious," Dallas coach Rick Carlisle said. "We'll find out [Sunday] where things are at, probably later in the day."
A source said that the symptoms indicate that Butler suffered at least a partial tear of the patella tendon, but the Mavericks won't be sure until they get the MRI results.
Rookie Dominique Jones, the Mavericks' first-round pick, will join the team in Cleveland for Sunday's game. Jones had been playing for the Texas Legends, the Mavericks' D-League affiliate, averaging 18.2 points, 5.2 rebounds and 5.0 assists in 10 games.
Butler was to stay in Milwaukee overnight and return to Dallas on Sunday to be further examined.
After Dallas' Jason Kidd hit a shot, Butler went down to the floor grasping his knee. He rolled over onto his stomach as play continued before Dallas was able to call a timeout.
The training staffs from both teams assisted Butler, who slapped the floor in frustration. Two minutes later, Butler -- from nearby Racine -- was helped to his feet and limped to the locker room under his own power.
In April 2007 at the Bradley Center, Butler broke his right hand while with the Wizards when he was challenging a shot at the backboard. He missed the rest of the season.
Information from ESPNDallas.com's Tim MacMahon and The Associated Press contributed to this report.