CHICAGO – The Bulls are battling for a playoff spot. The Celtics are chasing greatness.

The drama that unfolded at the United Center on Tuesday night belied the disparity of those goals.

When the Bulls’ 127-121 victory ended, their seventh straight home victory pushed them one-half game ahead of the Bucks for the final Eastern Conference playoff spot. And a victory over the defending NBA champions certainly can’t hurt confidence down the stretch.

The Bulls took the lead for good in a nip-and-tuck fourth quarter when John Salmons, who played brilliantly with 38 points, blew past Ray Allen for a reverse slam with 2 minutes, 28 seconds left. After Paul Pierce and Kendrick Perkins missed on the same Celtics possession, Derrick Rose finished a speedy drive with a lefty layup for a four-point lead.

Pierce, who led Boston with 37 points, sandwiched two baskets around a Brad Miller basket. But Salmons converted a conventional three-point play with 1:02 left.

Pierce made two free throws to make it 122-119, but Miller rebounded Rose’s miss and fed Salmons for a game-sealing layin with 29.8 seconds left.

The intense, back-and-forth game found a new level late in the third, when official Scott Foster whistled Bill Walker for a technical foul for trying to dunk on and then taunting Brad Miller after Pierce had drawn an offensive foul.

Foster signaled for another technical when Celtics coach Doc Rivers continued to argue the call and the sellout crowd of 22,107 jeered wildly.

“At home, we play with a different confidence and energy,” coach Vinny Del Negro said before the game.

Ben Gordon split the pair of technical free throws, but Salmons followed with a gorgeous spin move in traffic for a layup that tied the score at 80-80.

The Celtics responded the way they typically do-by attacking the rim-and quickly regained an 88-82 advantage. But Tim Thomas and Gordon sandwiched three-pointers around a Pierce basket, and Gordon tacked another technical free throw, this one for Boston’s illegal defense, to make it 90-89 Celtics entering the fourth.

That’s when the Bulls caught the technical foul bug as Foster hit up Miller with one for arguing.

Already playing without the injured Kevin Garnett, Leon Powe succumbed to a bruised right knee after playing just four minutes and Perkins experienced early foul trouble.

No problem: Mikki Moore and Walker contributed valuable reserve minutes, although Moore fouled out early in the fourth quarter.

But still, the Celtics kept coming.

“We’re in a playoff race,” Del Negro said. “Guys have to respond to the opportunity in front of us.”

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