A Ticket to ride

“I think it’s just the spirit of being back,’’ guard Rajon Rondo said of Garnett’s return. “It’s a whole other ballgame.’’

The Celtics (29-13) trailed by as many as 9 points during an opening half that was delayed several minutes while condensation was mopped off the court. They closed the half with a 10-4 run. The Celtics started the third quarter with a 15-6 run, Rondo’s drive making it 58-50 with 5:52 remaining.

The Clippers pulled within 64-59 on Rasual Butler’s second-chance 3-pointer with 1:23 to go. But the Celtics outscored the Clippers, 21-15, in the quarter, their best third-quarter margin since Dec. 22 (35-20), a 103-94 win over Indiana. Since that game, the Celtics had not outscored an opponent by more than 4 points (34-30 over Toronto) in the third quarter.

In fact, the Celtics celebrated their third-quarter performance Friday night, playing Portland even, 19-19, then eking out a 98-95 overtime victory to barely avoid a four-game losing streak.

“Last game, it didn’t seem like we lost three games in a row,’’ Rondo said of the Celtics’ rejuvenation. “It’s something we’re definitely feeling a lot better about, our defensive presence.’’

Garnett went out with a hyperextended knee in a Dec. 27 visit to Los Angeles, the Celtics losing, 92-90, to the Clippers.

“That was the game we noticed he was injured,’’ coach Doc Rivers said.

This time, Garnett seemed quite healthy, providing the foundation for the Celtics’ defense. This time, Rondo (16 points) concentrated on fronting Baron Davis, and Kendrick Perkins played physical against Chris Kaman. That defensive focus paid off in the second half.

The Celtics seemed to have the situation under control as Tony Allen’s steal and layup increased the lead to 71-61 with 10:49 remaining. But the Celtics would convert only once more from the floor over the next 5:37.

Ricky Davis’s free throw cut the Clippers’ deficit to 71-63, then Craig Smith scored the next 11 LA points. Smith made it 77-73, then Perkins missed two foul shots; but Ray Allen (15 points) chased down the rebound and fed Paul Pierce (22 points) for a 3-pointer for a 7-point advantage with 5:12 remaining.