Things could have gone the way it had in the past, with LeBron James guarding Pierce. Or the Cavaliers could have chosen to address the fact that Rajon Rondo had dismantled their defense by making their superstar chase the 6-foot-1-inch point guard.

“It really didn’t matter who was going to guard me,’’ Pierce said. “I was planning on being more aggressive.’’

Pierce’s defensive assignment and the fouls that came with it made it impossible for him to get anything going offensively, but in the Celtics’ 120-88 Game 5 win over the Cavaliers last night, Pierce was as aggressive offensively as he was at every other facet of the game, grabbing 11 rebounds and hounding James in the 42 minutes they were on the floor.

The 21 points were the most Pierce has scored all series, and even when things weren’t falling consistently (9 of 21 shooting), he kept looking for his shot.

“I wanted to be more aggressive getting set up in the paint,’’ Pierce said. “Just watching the film, there were more opportunities I could get in the paint and stop and get my mid-range jumper.’’

His defensive energy, however, was critical.

“He was active tonight,’’ said Kevin Garnett. “Paul was aggressive on both ends. I thought he was very talkative. It was so loud in here and one of the voices you did hear all night was his. I thought the fact that he helped on the boards, getting in there and getting loose balls, getting his hands on the ball, being aggressive and putting the onus on the defense, we’ll need that from him. That was the difference.’’

The minutes don’t matter to the 24-year-old Celtics guard.

“I’d rather play 48,’’ he said.

Celtics coach Doc Rivers is keeping an eye Rondo’s playing time, but when Pierce and Ray Allen get in foul trouble, he has to keep a playmaker on the floor.

“The foul trouble keeps hijacking Rondo’s minutes,’’ Rivers said. “Every time Paul or Ray gets into foul trouble, that’s another minute on the floor for Rondo. I feel we do need to give him a rest in the game.’’

Rivers has tried to rest Rondo during the long television breaks. “It’s funny how we’re trying to do it now is right before a quarter, even though it only says two minutes of rest, it’s really five or 10 minutes sometimes because the timeouts are lasting I think a half-hour now in games,’’ Rivers said.

Rondo addressed his workload with his usual sarcasm.

“It’s too many minutes, obviously,’’ he deadpanned.

Asked if he’s come to a decision, Pierce said, “Not at all. Everything’s going to happen the way it’s supposed to happen regardless of the direction the team has to go in. I’m fine with that. I told y’all I want to retire a Celtic. When the summer comes, we’ll worry about that.’’

If Pierce opts out of his contract, the Celtics would be $16 million under the cap, with $41 million in committed salaries.

“I haven’t really put no thought into it, truthfully,’’ he said. “I haven’t even taken one second to think about next month or next season. Right now the whole focus is the Cleveland Cavaliers, trying to advance, and win a championship.’’

The only other time three second-round series ended in sweeps was in 1999, following a lockout-shortened 50-game season. The Spurs swept the Lakers. The Knicks wiped up the Hawks. The Pacers breezed through the Sixers. And Portland (with Rasheed Wallace) beat Utah in six.

“I actually thought each series would be an interesting series,’’ said Rivers. “That tells you our knowledge. I don’t think anyone thought three sweeps. I think half of them thought this [series] would have been one. I don’t think anyone anticipated this.’’

Gary Washburn of the Globe staff contributed to this report; Julian Benbow can be reached at jbenbow@globe.com.