Tempers flared in the second quarter when a Celtics fast break ended with Kevin Garnett crashing to the parquet thanks to a Ron Artest foul. Garnett seemed to land on his surgically repaired right knee, and Rondo immediately jumped in and shoved Artest, earning a technical foul but also sending a message.

“I felt that Artest pushed Kevin,’’ Rondo said. “It wasn’t just a regular foul. We weren’t going anywhere, so in Kevin’s defense I pushed him back.’’

It was just the latest incident in a series that’s had its share of pushing and shoving. The dust settled there, though. Rondo went on to finish with 18 points and eight assists in the Celtics’ 92-86 Game 5 win. Artest was entirely ineffective, going 2 for 9 with 7 points and two rebounds.

Celtics coach Doc Rivers knew Rondo’s reasons, but didn’t agree with his actions.

“I don’t like that stuff,’’ Rivers said. “Let’s just play. It was physical. There was a lot of pushing going on, but we kept getting the technicals. You know, and I understand you want to take up for your teammates, and that is good, but strength sometimes is walking away, and I tell our guys that all the time. If you want to show toughness, toughness is walking away from all the other stuff.’’

Kendrick Perkins disagreed.

“I think Doc kind of got mad at him,’’ Perkins said. “But I told Doc that was the right play that he made. A hard foul on Kevin, and he retaliated. He’s taking up for his big man. It’s many ways to have an effect on the game. That could have taken Artest out the game, just having Rondo push him from behind. You never know how that could affect him.’’

Garnett said it was simply part of the game.

“At the end of the day it’s basketball,’’ Garnett said. “We’re not out here boxing. Everybody has played tough when it’s out here with three refs and a crowd full of people. We try to just tell everybody to control their emotions and protect one another, but you know, the way they call the game and the way they hand fines out and flagrants, all that goes out the window to be honest.’’

Things got testy again in the third quarter when Ray Allen and Derek Fisher were hit with double technicals. The two had argued earlier in the game, carryover from Game 4 when they got into a shoving match and were given warnings.

“You can never really back down,’’ Allen said. “You’ve got to push forward every moment you get, every opportunity you can.’’

“You know, he’s right,’’ Paul Pierce said. “What you just said, that’s been the truth for us throughout the regular season. I haven’t really seen too much of that in the playoffs, but coaches say things to try to motivate their team. He’s supposed to give them confidence. He’s supposed to say something like that. I probably would say the same thing if I was a coach in that situation. It doesn’t bother me at all.’’

Garnett, who had engaged in wars of words with Jackson and Pau Gasol earlier in the series, had “no reaction at all.’’

“I’m looking forward to Game 6,’’ Garnett said. “I couldn’t care less what Phil Jackson is talking about.’’

“I was trying for an offensive rebound and just trying to get my hand up trying to get out the crowd,’’ Perkins said. “Guys might try to bait you into getting tangled up and I was just trying to show the refs that I’m trying to run to the other end of the court.’’

Before the game, Rivers said Perkins’s newfound restraint gave him reason to believe the center can keep his temper in check next season.

“It’s a good thing,’’ Perkins said. “It means he’s got trust in me now, so it’s a good thing.’’

“When he got here, I was 26 years old, still learning my way, still coming into my own as a player,’’ Pierce said. “I think with him arriving here and just being in his presence over me, it’s helped me mature more as a player and as a person overall, and I think that’s helped my game out.’’

Julian Benbow can be reached at jbenbow@globe.com.