by Marcel Mutoni/@marcel_mutoni

The ’09-10 NBA season comes down to one final battle in Los Angeles on Thursday night, and one of the key participants may not be able to play.

Kendrick Perkins injured his right knee midway through the first quarter last night (and did not return), and even though he claimed that he’d try to give it a shot in Game 7, all indications at the moment seem to point to the Celtics playing without their defensive anchor in the do-or-die game.

ESPNreports:

Perkins was hopeful, saying: “I’m going to try to give it a go [on Thursday].” But a team source told ESPN.com’s Chris Sheridan: “He’s done.”

Perkins underwent X-rays during the Lakers’ 89-67 win that tied the series at 3. He suffered sprains to both his medial collateral ligament and posterior cruciate ligament, sources said. The team said that Perkins will be re-evaluated on Wednesday, which likely means an MRI to ascertain the extent of the damage.

Boston players also didn’t sound very optimistic, bracing for Game 7 without Perkins. But they refused to use his potential absence as an excuse for not closing out this series.”Perk brings rebounding and defense to the game, and toughness,” said Celtics captain Paul Pierce. “We lose that, but that’s not an excuse. We’re a mentally tough team. We’ve had injuries all year that we’ve dealt with. We know how to win when guys go down, so that’s no excuse for us.”

Celtics coach Doc Rivers didn’t disclose the severity of the injury or what he had been told, but didn’t sound optimistic, either. “I don’t know,” said Rivers. “It doesn’t look great, but I don’t know.”

UPDATE: The Boston Globe reports that Perkins out with torn ACL, PCL. Nasty…

Without Perkins, the Celtics would obviously be at a serious disadvantage inside. They struggled mightily in Game 6 (losing the battle on the boards 52 – 39), and watched Pau Gasol and company dominate the paint all game long.

Winning a Game 7 on the road is an extremely difficult thing to do; doing it without such a key component makes the task that much harder for the Celtics.