After the Chargers beat the Raiders, Gates said Rivers has a "very severe rib injury." On Monday, he tried to downplay his comments.
"I think some things I had said were taken out of context. I was just talking in terms of playing the game, just the typical soreness you have from playing in this league. I've been playing in this league a long time. I understand the process, the battles of what you have to put into a game, taking care of yourself physically."
"I'm no doctor, by [any] stretch. My job is to come out here and try to help us win. As far as Philip goes, anything pertaining to him or concerning him and his physical health, that's something maybe a doctor or a trainer or maybe himself can answer. Like I said, it was just me talking about his pure toughness, what I've known about him as a person."
Chargers coach Mike McCoy said he does not think Rivers' injury is serious as he has not missed practice this season.
"Philip's never missed a snap in practice, and he hasn't been in treatment with James," McCoy said, referring to James Collins, the team's head athletic trainer. "I would not say it's a severe injury. ... I think Antonio was trying to say how tough he is. I think Philip's one of the toughest quarterbacks in the game."
Rivers, 32, has not been listed on the injury report by the San Diego Chargers this season. He has completed 66.8 percent of his passes for 2,544 yards, 21 touchdowns and eight interceptions this season.
The Chargers are 6-4 and in third place in the AFC West. They will host the St. Louis Rams on Sunday at 4:05 p.m.