Celtics forward Paul Pierce drives against the Chicago Bulls' John Salmons, left, and Joakim Noah during Game 2 of their playoff series in Boston on Monday. (Elise Amendola/Associated Press)

Ray Allen picked the perfect time to snap out of his shooting slump.

Allen made a tiebreaking three-pointer with two seconds left and finished with 30 points, leading the Boston Celtics to a 118-115 win over the Chicago Bulls in Game 2 of their NBA playoff series Monday night.

Ben Gordon nearly carried Chicago to a 2-0 lead in the best-of-seven series. He scored with 12.3 seconds left to tie it, and had a playoff career-high 42 points. But then Boston set up a play for Allen, who took a pass from Rajon Rondo and connected from the right side.

Allen had just four points on 1-for-12 shooting in Boston's 105-103 overtime loss on Saturday but scored 28 points after getting some advice from coach Doc Rivers at halftime.

"Doc said going into the half, 'Be aggressive, but let it come to you,"' Allen said. "I never think I'm not in my rhythm. It can be a grind as a shooter. As a scorer, you're always trying to find something."

Allen vs. Gordon

Allen and Gordon each had several clutch baskets in the second half as the former University of Connecticut guards battled for control of the game. After Tyrus Thomas missed a shot from midcourt as time expired, Allen headed for his bench, where injured Kevin Garnett delivered a couple of congratulatory slaps — to his head and chest.

Allen said he doesn't like "being made a fuss over." But that was unavoidable after he broke out of his shooting slump. He scored just four points on 1-for-12 shooting and missed the final shot in Chicago's 105-103 overtime win Saturday.

"It felt like we were at UConn in the summertime playing pickup," Gordon said. "He is a great shooter, and I knew he would break out eventually."

The Bulls showed they could compete with the Celtics, who could be without Garnett (strained right knee) for the rest of the playoffs.

"We got a split, and that's tough to do against the defending champs," Gordon said.

Consecutive 3-pointers by Gordon gave the Bulls a 109-104 lead before the Celtics rallied. Glen Davis made two free throws, and Rondo connected on a long jumper to give Boston a 112-111 lead with 1:01 to play.

Gordon followed with a 16-foot jumper, and Allen countered with a 3-pointer that put Boston ahead 115-113 with 25.3 seconds remaining.

Then it was Gordon's turn. He connected from near the foul line before the Celtics called a timeout to set up their final play.

Rondo dribbled on the left side, and Allen worked himself free, caught the pass in rhythm and converted as the crowd went wild.

On his way to the locker room after Thomas missed the last shot for Chicago, Rivers shouted, "Yeah! Yeah!", pumped his fist and exchanged high-fives with fans. Then, headed to his post-game news conference, Rivers joked, "Nice and easy; never a doubt."

Rivers said the Allen-Gordon shootout "almost looked like they turned it into a personal battle — you know, who's the best UConn player to ever play. And it was amazing."

And physical.

"We were exchanging jabs there, and I don't mean shots," Allen said. "I mean he caught me with an elbow; I got him right back with an elbow. It was ... competitive."

The next two games of the series are scheduled for Chicago on Thursday night and Sunday.