WALTHAM, Mass. — The Celtics had a light practice yesterday at the Sports Authority Training Center.

As the No. 1 seed in the playoffs thanks to an NBA-best 66-16 regular-season record, Boston is preparing to take on the eighth-seeded Atlanta Hawks — a team that the Celtics swept during the regular season (3-0) by an average 14.3 points per game.

Yesterday’s practice consisted mostly of watching film of the Hawks, running and trying to stop a fast-break offense, and was capped off by a free-throw shooting contest, which Ray Allen won by besting Tony Allen in the finals.

“We’re going over a lot of their plays and breaking down individuals down to the tee,” Boston captain Paul Pierce said. “We’re doing a lot of studying…so the next three days are going to be a lot of preparation and a lot of studying for us.”

There was a lot of fun and games at practice, but the Celtics are not taking the Hawks lightly even though Atlanta has the worst record (37-45) among the playoff teams.

Boston coach Doc Rivers said he’d put the Celtics through a much tougher practice today.

The Hawks feel like they are a team that should not be overlooked.

Atlanta guard/forward Josh Childress told the Associated Press after it was announced that Boston was going to play Atlanta in the first round that the Hawks had an excellent shot at upsetting the heavily favored Celtics.

“They’re a team that obviously is very good,” Childress said. “I like our chances. We match up pretty well with them. In the games we played them, we have played well, but we weren’t able to finish the game. I feel like we’re still trying to get better at that. We’re a team that has nothing to lose. We’re going to go out there and just fight.”

Childress’ teammates backed up his statement.

“We’d be fools to think it’s not possible,” Hawks forward Josh Smith told The Atlanta Journal-Constitution on Wednesday. “We’d be bigger fools not to believe in ourselves, especially after the way people have bashed us the past few years.”

Garnett not at practice

All-Star forward Kevin Garnett missed yesterday’s practice for “personal reasons.”

“I think he had personal matters today, so we’ll probably see him [today] or the next day,” Pierce said. “He’ll be back. I’m sure he’s just taking care of what he needs to take care of, and then he’ll be with the team. You know it’s probably very important to him because Kevin is a guy that will be here.

“Kevin doesn’t like to miss practice, so I know it’s a good reason [that he’s not here].”

Extra points

Rivers received unexpected honors this week.

Rivers and Los Angeles coach Phil Jackson were named their respective conference coach of the month for April.

roblee@projo.com