The AP reports:

Celtics center Kendrick Perkins out for NBA Finals Game 7

Boston center Kendrick Perkins’ sprained right knee will keep him out of Game 7 of the NBA finals.

Celtics coach Doc Rivers confirmed Wednesday that his starting center won’t play in the season finale against the Los Angeles Lakers on Thursday night, dealing a blow to Boston’s hopes of winning its 18th championship.

InsideHoops.com says:

I’d have favored the Lakers over Celtics in a Game 7 in Los Angeles anyway, but with Perkins out it obviously makes Boston even more of an underdog.