ATLANTA — The glow from the Atlanta Hawks’ first playoff victory of this century — the last came in May of 1999 — was still burning yesterday.

At a light workout at Philips Arena, the Hawks patted themselves on the back for their efforts in a 102-93 win over the Celtics in Game Three of their first-round series. The Hawks seemingly did everything right. They shared the ball (28 assists, 36 baskets), ran the floor for eye-popping dunks, shot well from the outside (10 threes, 5 by Joe Johnson) and held the Celtics to 44-percent shooting.

But pulling off a repeat performance will be an even greater test. Even so, the proper focus seems to be intact. Scrawled on the marker board in the Hawks’ dressing room late Saturday night were three words: Don’t Be Satisfied. They can’t afford to be with a critical Game Four set for tonight.

After getting knocked around handily in the first two games of the series, the Hawks saw the Celtics crack a bit in Game Three. Asked whether the Celts seemed rattled through the second half, Johnson answered, “Yes, I do. I think in the fourth quarter they really couldn’t make a run on us.”

Johnson pointed put that Atlanta pulled away thanks to fine play at both ends of the court. The Hawks led by 10 points after three quarters and limited Boston to 19 fourth-quarter points.

“They came down and we just stopped them. We came down and scored,” Johnson said of the big second-half swings. “We were just making big shot after big shot. Then I thought they just finally kind of gave up a little bit.”

Pierce won’t take bait

Paul Pierce says he won’t fall for the taunting that came his way late in the game courtesy of Atlanta rookie Al Horford. After swishing a shot with just 22 seconds left, Horford barked at Pierce as he danced his way back up the floor.

“He’s a young player. He’s getting caught up in the moment,’ said Pierce. “He’s got these little antics that he does, but we’re not getting caught up in that. We’re just going to keep playing basketball.”

Lack of focus

The Celtics agreed that a lack of mental focus hurt their cause Saturday. They watched examples of breakdowns and mental errors in a lengthy film session yesterday.

“Composure is everything,” said Kevin Garnett. “This game is as much mental as it is physical.”

Pierce agreed. “I think we got a little frustrated and rushed a lot of shots where we didn’t move the ball once we got down. It’s something we can correct.”

Garnett said that a renewed focus on defense could solve plenty of problems. Garnett and Kendrick Perkins (with reserves Leon Powe and P.J. Brown) have struggled defending the Hawks’ Josh Smith and Horford at times in the series and especially in Game Three, when the two young big men combined for a whopping 44 points and 23 rebounds. Garnett can shadow Smith, but when the lefty drifts out and bangs home 3-pointers (he made three in Game Three), Garnett leaves rim protection inside to Perkins or whoever else is on the floor at center.

“I think we have to get back to our defensive mentality,” Garnett said. “When we play defense like we know we can, it’s very hard to beat us so look for us to hang our hat on that (tonight). Obviously execution is important on both ends.”

Game Five time not set

The time for Wednesday’s Game Five in Boston will depend on the result of tonight's Lakers-Nuggets game in Denver. If Los Angeles completes a four-game sweep, the Celts and the Hawks will tip off around 8:30. If Denver comes back to force a Game Five, the start time in Boston moves up to 8.

Another win by the Hawks would mean a return to Atlanta for a Game Six on Friday night.

It would be helpful if the Celtics could win the next two games and get ready for the next round of the playoffs. The winner of this series is matched up against the Cleveland-Washington series, and the Cavaliers took a giant step toward moving forward with a big win in D.C. yesterday. Lebron James and Co. now lead the series, 3-1, and can close out the Wizards on Wednesday in Cleveland.

kmcnamar@projo.com