LOS ANGELES — Doc Rivers’ parting words to the Celtics during their team meeting on Sunday were simple but critical.

“He said rebounding is the key,” Kendrick Perkins told WEEI.com prior to Game 2 of the NBA finals. “Those were his last remarks, that rebounding was the key.”

The Celtics were outrebounded 42-31 by the Lakers in their Game 1 loss. Not only did they lack aggressiveness on the glass, they let the Lakers drive the lane and get into the paint with ease.

Neither can happen in Game 2 if they want to go back to Boston with a win.

“I think we’ve got to control dribble penetration,” said Perkins. “All five guys have got to attack the basket and we’ll be alright.”