With 49.9 seconds left in the quarter, Wallace exploded at official Bill Spooner, although it wasn’t about a foul call. Apparently Wallace was angry that LeBron James cursed Spooner for a non-call and was not assessed a technical.

Wallace had to be restrained from Spooner, then barked at official Rodney Mott. When Rivers attempted to restrain Wallace, he began screaming at his coach, to the shock of his teammates. Wallace received a technical and did not return to the game.

He was at practice yesterday, taking his customary midrange jumpers. Rivers said they had a conversation, although Wallace didn’t exactly apologize.

“We just talked about the situation, trying to control yourself,’’ Rivers said. “Understanding that at the end of the day, when stuff like that happens, even when you think you are in the right, you’re still in the wrong because it hurts the team. Rasheed’s emotional. He’s been emotional and some of that won’t change.’’

When asked what angered Wallace, Rivers said, “I’m not going to get into that, but I know what he was upset about.’’

Rivers has tolerated Wallace’s behavior this season, and the veteran forward did come to Boston with a well-earned reputation as occasionally volatile. But this is the first time Wallace lashed out at Rivers, making for an uncomfortable environment as the game advanced to the fourth quarter.

“You can’t focus on the one [player] at that point [in the game],’’ Rivers said. “And then after the game and the next day you have a conversation and you try to get that right because emotionally it’s not personal. He gets along great with his teammates but when you have an emotional hijack, you don’t get along well with anybody at that moment and I understand that. I’ve been there.

“He just said, ‘Hey, I know I should have controlled myself,’ ’’ Rivers continued. “I don’t know if that’s an apology, but I wasn’t looking for one. I didn’t need an apology.’’

Robinson has shot fewer than 39 percent as a Celtic and hasn’t scored in double figures since March 12. The club expected scoring punch off the bench and solid point guard play but Robinson has been tentative offensively. Rivers said he was upset that Robinson attempted a 3-point shot with 19.9 seconds left in the first quarter Friday against Houston with 19 seconds remaining on the shot clock.

Daniels has struggled since returning to the lineup in February after recovering from a torn left thumb ligament. He was signed to spell Rajon Rondo and provide solid defense, but he has gradually lost Rivers’s confidence. He averaged 9.4 points in nine games after returning from injury, but has averaged 3.7 in 18 games since.

“Their role is to work every day in practice, but there will be a day or a time you’re going to need them,’’ Rivers said. “Somebody will get in foul trouble or someone may not be playing well. Yeah, right now they are [out of the rotation]. But that doesn’t mean they won’t be back in it.’’

Allen also added 7 points and has 19 the past two games. After missing early parts of the season recovering from right ankle surgery, then playing inconsistently most of the year, Allen has finally captured Rivers’s attention.

“It’s when you are in school, you take tests, quizzes, and I have been taking quizzes all year,’’ Allen said. “Just being in games, in situations that affected long term, I passed some of those tests and they are paying off right now.’’

Gary Washburn can be reached at gwashburn@globe.com.