Rivers argued vehemently after referees called a flagrant foul against Glen Davis Monday, earning a double technical and immediate ejection. But he might be even more flabbergasted by the fine.
The NBA confirmed Wednesday night to ESPNBoston.com that the flagrant had been downgraded to a normal foul, and Rivers said the league called him to apologize.
"They admit that the ... call was wrong," Rivers said before the Celtics met the New Jersey Nets Wednesday. "Of all the fines I've ever had, this is by far the most disappointing. I just don't get this one. I watched a couple of coaches last week run out on the floor and [they received] no fine. I get fined for being right."
Referees called a flagrant foul after Davis took down Marvin Williams midway through the third quarter. Rivers erupted when he learned of the call, emphatically gesturing at the officials after being ejected.
Rivers admitted he wasn't in the mood to listen to the league's apology.
"I didn't want to hear the explanation when they called, honestly. I was not in the mood," Rivers said. "I didn't let them [explain] because there was no explanation.
"They said I stayed out on the floor too long or whatever, which I didn't do. I didn't swear, [I just] kept saying, 'It's an awful call,' so I'm perplexed by the fine. I was perplexed at the time and so I still am."
Before Rivers could be herded down the tunnel to the locker room, soft-spoken assistant coach Armond Hill drew yet another technical.
The volatile series left Atlanta with five free throws -- it made four -- and possession of the ball, helping the Hawks trim Boston's 10-point lead to a 67-61 advantage with 6:16 to play in the third quarter.
Atlanta tied the game before the end of the quarter, then pulled ahead in the fourth, making Rivers' tantrum sting that much more.
"I told the guys after the game, No. 1, that's always on me," Rivers said Monday. "I don't think I should ever get thrown out. I don't know when the last time I was thrown out was, actually. I don't care how bad you think the calls are at the moment, you know, somehow you have to try to rein yourself back in.
"Honestly, I reacted -- I was so shocked at what they were calling. I thought they were talking about whether it was a breakaway or not. The last thing I had in my mind was a flagrant. I didn't even think that was part of the discussion. So I was so surprised by that I reacted, and I never should have."
Information from the Associated Press was used.