ATLANTA — The Boston Celtics looked like the fresh team, not the one playing back-to-back games on the road.

The Atlanta Hawks? No one’s quite sure what’s going on with this listless bunch.

Nate Robinson had 16 points and 10 assists filling in for Rajon Rondo and the Celtics blew out Atlanta right from the start, racing to a 26-point lead in the first quarter on the way to a 99-76 rout Monday night.

This one was over before many fans had even settled into their seats. Paul Pierce hit a jumper, Kevin Garnett made another and the Celtics were off and running.

Pierce said everyone in green was still smarting from a one-point loss at Toronto the day before, and they hadn’t forgotten what happened last season, when Atlanta swept all four meetings. Talk about making a statement.

“The whole bus drive from Toronto to the airport to customs — even this morning’s shootaround — you just saw the focus,” Pierce said. “Guys were (ticked) off. That’s the way we should be every night. We should never have to use losses to motivate us.”

Atlanta missed five of its first six shots, and Boston had a double-digit lead before the game was 4 minutes old. Shaquille O’Neal’s dunk made it 13-3, prompting the first of three timeouts first-year coach Larry Drew called in the opening quarter in desperate attempts to slow the Celtics.

Nothing worked. Boston made 18 of 25 shots, the Hawks just 4 of 17 and it was 39-13 at the end of the first.

“This was very embarrassing,” said Drew. “Very, very embarrassing. Very embarrassing. If I had one word to sum it up: embarrassing.”

The Hawks have lost 6 of 8 since a 6-0 start, and a disturbing trend is emerging for a team that finished third in the Eastern Conference last season and decided to stand pat, other than fire Coach Mike Woodson and promote his top assistant. Atlanta has yet to beat a team with a winning record, and this one was never close.

The Celtics snapped a modest two-game losing streak even without Rondo. He didn’t dress because of a strained left hamstring, but Robinson did a dead-on impression making his second straight start at the point, sparking the Celtics with eight points and five assists in the opening period.

Garnett scored 17 points, while Pierce and O’Neal chipped in with 13 apiece.

“I wish we could bottle this and put it on the shelf or something,” Garnett said. “It was imperative to come out with a lot of energy. We played defense for 48 minutes.”