"We played awful in the first half, but we had a strong third quarter and was able to cut the lead down a little bit," Jack said. "Then guys really showed what they are made of in the fourth quarter.
"We dug in defensively," he added. "We had been struggling all game on defensive rotations and just simply keeping the ball in front of us. I think guys really took the challenge to stay in front of their own guy and then when the ball was on the rim going in for the rebound."
Troy Murphy had 22 points and 15 rebounds for the Pacers, who trail Chicago by two games for the final Western Conference playoff spot - but have to overtake four teams, including the Bulls, to get there. Leading scorer Danny Granger missed his ninth game because of a torn tendon in his right foot.
Clippers rookie Eric Gordon had 35 points and six assists against his hometown team after missing four games with a bruised left shoulder. Zach Randolph also rejoined his teammates from Indianapolis, where his father died Thursday because of heart problems after being hospitalized since Feb. 17.
"I got back this morning. It was real difficult leaving my family, getting on a plane and flying all the way back here from Indiana. But that's what my dad would want me to do," an emotional Randolph said after the game. "He would want me to take care of my business. Me and my pop were really tight. I think about him all the time. But he's in a better place now and he's not suffering anymore."
Randolph, the Clippers' leading scorer, came off the bench for the fourth time since he was acquired in a trade with the New York Knicks on Nov. 21, scoring 20 points and grabbing 10 rebounds.
Clippers rebounding leader Los Angeles' Marcus Camby didn't play because of migraines that forced him out of Wednesday's loss to Memphis after one quarter. Point guard Baron Davis (sore right hamstring) and reserve Ricky Davis (sore left knee) also were sidelined.
Trailing by nine with 4:54 to play, Indiana pulled ahead 106-105 with 45 seconds remaining on a three-point play by Jack that capped a 12-2 run - which Jack began with a 3-pointer.
The fourth-year guard, acquired in a trade with Portland in July, then stole the ball from Clippers rookie Mike Taylor and Brandon Rush put up a 3-point shot from in front of Los Angeles' bench. He missed it, and the Clippers called a timeout to set up a play with 5.2 seconds to go.
Marquis Daniels made the game-saving defensive stop, blocking Gordon on a driving layup as the horn sounded.
"We had good ball pressure on him that forced him into a tough shot and he was forced to try to make something happen," Daniels said. "I just got good timing and got a hand on it. I knew he was going to take it. He had things going well for him."
It was a bitter ending for Gordon, who was born in Indianapolis, played his high school ball there and was drafted by the Clippers following his freshman year at Indiana.
"Murphy and Jack made a couple of big 3s that got them close," Gordon said. "And when you get down to 30 seconds in a close game like that, it's anybody's game. We just let that game go."
Gordon made nine of 12 shots in the first half and scored 22 points to help the Clippers build a 64-51 lead against the last-place team in the Central Division. He had 32 by the end of the third quarter.
"I don't like to miss too many games, so I was just really excited to get back and play," Gordon said. "I was settling on this date to come back. But I was ready anyway, whether we were playing the Pacers or not. We've been really short-handed, and we were short-handed again tonight. So I just really wanted to get it going early."
Clippers coach Mike Dunleavy didn't get a chance to improve on his 12-6 record against his son, because Mike Jr. underwent surgery last Friday to remove a bone spur and repair a torn tendon in his right knee.
Notes: Jack's 27 points against the Clippers in a double-overtime loss at Indiana on Dec. 19 marked the first time he led the Pacers in scoring this season. He has done it seven times since, twice when sharing high-point honors. ... The Clippers used their 28th different starting lineup. Every player on the team has started at least one game except for G Alex Acker, who was obtained Feb. 16 in a trade with Detroit; and C Cheikh Samb, who was waived the same day. ... Murphy needs three defensive rebounds to break the Pacers' club record of 594, set by Jermaine O'Neal in 2002-03.