Kawhi Leonard was ruled out of Tuesday night's game against the Boston Celtics because of back spasms that hampered the LA Clippers All-Star forward during warm-ups.

Leonard warmed up but left the TD Garden court shortly before tipoff with his back not feeling right. He was replaced in the starting lineup by Reggie Jackson. The Clippers then announced late in the first quarter that Leonard was ruled out for the game with the back issue.

Leonard missed two games early this season because of a mouth laceration. He sat out another two games because of health and safety protocols from contact tracing for COVID-19. And he missed three games in mid-February because of a lower left leg contusion. He returned from that injury and played in six straight games until the back spasms kept him out Tuesday.

The All-Star is averaging 26.8 points, 6.3 rebounds and 4.9 assists this season.

Also Tuesday, the Clippers lost Marcus Morris Sr. for the second half against the Celtics because of a concussion he suffered after appearing to take an inadvertent elbow to the head late in the second quarter.

The Clippers play at Washington on Thursday before entering the All-Star break.