EL SEGUNDO, Calif., June 13 (AP) -- The Boston Celtics aren't sure if center Kendrick Perkins will be able to play in Sunday night's Game 5 of the NBA finals against the Los Angeles Lakers.

Perkins strained his left shoulder in Boston's 97-91 victory Thursday night. He is averaging 4.5 points in the series.

Celtics point guard Rajon Rondo also aggravated his sprained left ankle, and star forward Paul Pierce rolled his right ankle in Game 4, but the captain stayed in the game. Both are day to day.