There was a constant, nagging sound that followed Hawks players from the light practice Tuesday morning to the locker room before the game that night to the team huddles during Game 2 against the Celtics.

The voice told them that no Rajon Rondo didn’t mean they could relax.

“I will be that little birdie on their shoulder tonight just to remind these guys that we’re going to have to have a supreme effort from everybody tonight,” Hawks coach Larry Drew said. “Because this Celtics team, they’ve been in this situation before [and] they are going to come out and give us their best game.”

The Celtics did as Drew expected, and the Hawks couldn’t handle it. Boston finished stronger for an 87-80 victory Tuesday in the first-round Eastern Conference playoff series.

Game 3 of the best-of-seven series is Friday in Boston. The Hawks now will have to win at least one game there to advance to the second round.

The Hawks will await word on the status of forward Josh Smith for that game. He suffered what the team said was a sprained right knee in the final five minutes of Game 2.

Rondo, Boston’s All-Star point guard, sat out Game 2 after the NBA suspended him for bumping an official during Game 1. That still left Boston with All-Star forward Paul Pierce and Kevin Garnett, both of whom are finishing Hall of Fame careers.

The Hawks relaxed at times during the regular season when the opposition was at less than-full strength. Most notably, the Heat won at Philips Arena with stars Dwyane Wade and LeBron James on the bench in street clothes.

Would the Hawks stay focused in the absence of Rondo now that it’s the playoffs?

“I would like to think so,” Hawks forward Marvin Williams said before Game 2. “I think everybody understands what’s at stake at this point.”

It turned out the Hawks’ defensive intensity was strong throughout. It was the offense that wouldn’t allow the Hawks to ease past Boston.

The Hawks led 65-54 in the third quarter, but then a long series of poor possessions resulted in a scoring drought. Hawks reserves struggled to create good shots while Pierce and Garnett went to work until Boston forged a 66-66 tie early in the fourth quarter.

That set up a fierce, physical, finish over the final eight-plus minutes. Pierce’s layup in transition gave Boston a 72-70 lead, its first since 34-31 in the second quarter.

The score was tied 72-72 when Boston’s Marquis Daniels shook free for a dunk, Mickael Pietrus’ steal of Joe Johnson’s pass led to Pierce’s layup, and Pierce made a pull-up jump shot. Suddenly the Celtics led 79-72 with 3:30 to play and their fans in the arena

After Ivan Johnson’s 3-point play, Pierce made another pull-up jumper for an 81-75 Boston lead. Joe Johnson made one of two free throws to trim the Hawks’ deficit to 81-78, but Garnett made two free throws and Pierce added two more after Johnson missed a 3-point try.

The Hawks’ last gasp came up short when Jeff Teague missed an open 3-point attempt.

The Celtics, who won the 2008 NBA championship and lost in the 2010 Finals, couldn’t recover in Game 1 on Sunday after the Hawks ran to a big early lead, but they finished the comeback this time.

“They are still a good team,” Teague said before the game. “We approach it the same. We’ve got to lock in and get another win.”

Teague did his part, using his speed to inject life into the Hawks’ offense when it sagged while scoring 18 points. Johnson scored 22 points but had the key turnover late and managed just five points in the fourth quarter.

Pierce took over some of Rondo’s ball-handling duties because he’s skilled enough to serve as the point guard. He showed off his all-around game while pouring in 36 points and adding 14 rebounds and four assists.