Ben Gordon scored 22 points, hitting the tying 3-pointer in the first overtime, and the Bulls beat the defending champions 121-118 in double overtime Sunday to tie their first-round series at two games apiece.

The teams split two tight games in Boston, before the Celtics blew out the Bulls in Game 3. This time, they stretched the drama into a second overtime.

"Everybody I'm talking to is saying this is the most exciting series that they're watching right now," Gordon said.

It's tough to argue.

Derrick Rose added 23 points, 11 rebounds and nine assists. John Salmons scored 20 points after a slow start, hitting four free throws in the final 26 seconds of the game and blocking Paul Pierce's tying 3-pointer.

Boston's Ray Allen buried a 3-pointer with 9.8 seconds left in regulation to tie it at 96 before Rose missed a potential winning fadeaway in the closing seconds. Gordon came through with 4.5 seconds left in the first overtime, hitting a 3-pointer over Pierce to tie it at 110, and the Bulls never trailed in the second OT.

Salmons hit two free throws with 26 seconds left and, after a 3-pointer by Pierce, he hit two more at the line. After a timeout, Pierce got the ball on the left side but couldn't shake Salmons, who deflected his 3-pointer.

It was a dramatic end to another dramatic game. The series goes back to Boston, where the Bulls took Game 1 in overtime and the Celtics won Game 2 by three, on Tuesday.

"It's 2-2 and we're in a fight," Boston's Rajon Rondo said. "Give them a lot of credit. They stuck with it. They fought back. They executed down the stretch very well and we didn't."

Pierce led Boston with 29 points, although he was just 9-for-24. Allen added 28, and Rajon Rondo again hounded the Bulls, finishing with 25 points, 11 rebounds and 11 assists - his second triple-double of the series.

"We've been here before," Allen said. "That's (what) bothered me so much about this one, because we had opportunities."

Rose, who was outplayed by Rondo in the previous two games, again had trouble hanging onto the ball. He committed seven turnovers for the second straight time, but made up for it with 13 points in the fourth quarter.

Gordon also came through late even though he strained his left hamstring in the second quarter and is scheduled for an MRI on Monday.

Kirk Hinrich added 18 points while containing Pierce. Tyrus Thomas had 14 points and 10 rebounds, and Joakim Noah scored 12 while grabbing 10 boards. The Bulls prevailed despite missing some key free throws down the stretch and were 26 of 35 overall.

"We've got a lot of fight in us, and I'm really happy for the young guys," Gordon said.

The Celtics led by five in the first OT and were still up 110-107 after Allen hit two free throws with 9 seconds left. They were then supposed to foul, but instead, Gordon buried another dramatic 3.

He got the ball near the top of the key and dribbled to his right, hitting the tying shot over Pierce. Rondo then missed a jumper, sending it into a second OT.

"We always foul, but even when you screw it up, they've still got to hit the shot and Ben Gordon made a hell of a shot," Celtics coach Doc Rivers said.

In the second OT, Noah dunked over Glen Davis to make it a four-point game with 1:26 left. Pierce missed a 3-pointer, and with the crowd chanting his name, Noah sank a free throw to make it 117-112 with 35 seconds remaining.

Pierce converted a three-point play to pull Boston within two, but Salmons came up big at the line before making the big block to preserve the win.

"This team has a lot of heart, has a lot of character," Salmons said.

Notes: Chicago's Brad Miller was nearly ejected after a skirmish with Davis early in the fourth quarter. He grazed Davis with a forearm to the head after taking a hard foul and was initially assessed a flagrant foul 2, but the officials reduced it to a technical. ... Rondo, averaging a playoff-leading 4.0 steals entering the game, had two.