Boston Celtics guard Leandro Barbosa sustained a non-contact left knee injury late in the third quarter of Monday's game against the Charlotte Bobcats according to the team, and the initial outlook is not encouraging.

Barbosa is expected to be reevaluated on Tuesday in Boston, but teammate Kevin Garnett suggested to reporters after the game that the injury could threaten Barbosa's season.

"It's tough, man. It's tough all the way around," Garnett said. "You work with these guys and all of a sudden you see a season-ending injury. We're grinding right now, on top of a back-to-back emotional game. Tonight was a very tough game."

Barbosa left the Celtics' locker room under his own power but limping, and declined to talk to reporters.

"L.B. was really starting to play great for us, so let's just hope he's OK," Celtics coach Doc Rivers told reporters in Charlotte. "It doesn't look great, but we'll see. We'll know more [Tuesday]."

Barbosa went to the ground in pain after planting awkwardly after a drive to the baseline. Teammate Fab Melo and team trainer Ed Lacerte carried Barbosa to the sideline and then to the locker room, the player apparently unable to put pressure on his injured leg.

Barbosa did not return to the game and iced his knee in the locker room.

The Celtics are already playing shorthanded after both Rajon Rondo (ACL) and Jared Sullinger (back) were lost for the season recently.