The Celtics were sending mixed messages last night on the condition of Leandro Barbosa, who injured his left knee and left the 94-91 loss to the Charlotte Bobcats in the final minute of the third quarter and might require surgery. According to a source, there is a strong possibility Barbosa’s season is finished, but the team is waiting for tests to be conducted before anything is certain. Barbosa traveled with the team back to Boston last night and will get an MRI this morning. Coach Doc Rivers said it’s “not looking great” for Barbosa, and a sullen Kevin Garnett said he was told it’s “pretty much” the end of the season for the speedy guard. If that’s true, Barbosa will be the third Celtics player to suffer a major injury requiring surgery in the past three weeks, following Rajon Rondo (knee) and Jared Sullinger (back). Barbosa’s injury occurred on a drive, and there appeared to be no contact. He later limped out of the dressing room, declining comment. “It’s the knee we think, but we don’t know,” Rivers said. “It’s not looking great, but we’ll see. There’s nothing we can do. Guys are playing hard. (Barbosa) was really starting to play great for us. So let’s just hope, you know, he’s OK. It doesn’t look great, but we’ll see.” Garnett clearly was affected emotionally by the situation. “I don’t really have much to say. We’re falling like flies right now,” Garnett said. “We got the news when we came in the locker room. You know, obviously, it’s tough. You’re messing with these guys, and then all of a sudden you’re seeing season-ending injuries. It’s tough, man. We’re grinding right now. I think the blow of Barbosa right now is kind of the fog or the cloud that’s in the room right now.”