SAN DIEGO -- Philip Rivers' ribs are hurting.

So said Antonio Gates, the San Diego Chargers' star tight end, who let it slip last Sunday that his teammate and friend has been dealing with "a very severe rib injury" for the last three to four weeks.

The injury report sort of said so, listing Rivers as having a "chest" affliction.

Going into today's home game against the sack-happy St. Louis Rams, don't expect any clarification from Mike McCoy, the second-year coach who bristles when injuries are discussed and repeatedly reminds reporters that he's not a doctor.

On Monday, McCoy said Rivers hadn't been treated at all this year for a rib injury. Asked Wednesday if the QB received treatment for the chest injury listed on the practice report, McCoy said: "He looked great out there. He'll be ready to go."

The "chest" injury can't be to Rivers' heart, because no one has ever questioned his toughness. He played the 2007 AFC championship game with a torn ACL in his right knee. He went back into Sunday's game despite having his leg rolled up on and then having the wind knocked out of him.

It can't be to his lungs because Rivers can talk up a storm.

So the ribs are the next best guess.

That would explain Rivers' plunging stats. In helping San Diego to a 5-1 record, he had a passer rating of 123.8 or better in five straight games and completed 71.4 percent or more of his passes three times.

San Diego has lost three of its last four. Rivers twice failed to complete even 55 percent of his passes and hasn't cracked a 100 rating. He was awful in a 37-0 debacle at Miami three weeks ago.

"As a buddy he was trying to give a compliment but it ended up, 'Oh, what's the matter,' '' Rivers said of Gates' comments. "I can honestly say there is nothing going on hindering me in any way. It's part of playing the position and I will be fresh and ready to go on Sunday."

The Chargers have scored only 13 points in their last two games and have struggled on third down.

McCoy said the playbook wouldn't be compromised due to Rivers' injury.

"Philip is playing on Sunday. We've got a great plan and Philip is fine," he said.

Here are some things to watch for when the Rams visit the Chargers:

• Half rack of ribs: Chargers offensive coordinator Frank Reich, a former QB, said he played with banged-up ribs. "Yeah, I mean, you play this game long enough you play with a banged-up everything. Sometimes it's more banged-up than others; there are varying degrees, but you just keep playing ball."

Reich said Rivers' injury hasn't compromised his game. "He is a tough guy, Obviously a lot has been said about it. Truthfully, I've been in two years and we've talked about every subject in the world except injuries. He never talks about stuff like that -- he is old school."

• Full rack of ribs: Rivers better wear a flak jacket because the Rams have piled up 13 sacks in the last three games. They dropped Peyton Manning twice last week, Carson Palmer three times the previous week and Colin Kaepernick a whopping eight times three weeks ago.

Rivers was sacked twice and hit several other times by the Raiders.

Robert Quinn leads the Rams with six sacks while Aaron Donald has four.

"They are just playing. They are just staying after it," Reich said.

• Shaun Hill: The 34-year-old Rams quarterback earned a second straight start after his turnover-free outing in an upset against Manning and the Broncos, his first victory since 2010. The last time the journeyman had consecutive starts was four years ago when he subbed for injured Matthew Stafford.

"Comfortable is not something I've had the luxury of having in the NFL, that's just kind of how my career has gone," he said. "I think I'm probably best in that role, not exactly comfortable. I'm being honest."

Hill was 20 for 29 for 220 yards with a passer rating of 102.7. He had a 63-yard touchdown pass to Kenny Britt.

• It works both ways: Chargers defensive coordinator John Pagano will match wits with Rams offensive coordinator Brian Schottenheimer, who was San Diego's quarterbacks coach from 2002-05 under his dad, Marty.

"He's really grown in this profession," Pagano said. "You've seen him grow from when he was here. He's a heck of a coach.

Chargers backup quarterback Kellen Clemens was with the Rams from 2011-13.

"It is huge any time you can get a guy and communicate with our guys about certain things," Pagano said about Clemens running the scout team in practice.

• Hike: With Chargers center Rich Ohrnberger looking doubtful due to back and ankle injuries, rookie Chris Watt would get the call.

It'll be a big deal for the former Notre Dame player to call out the right blocking assignments for the struggling line against the Rams' pass rush.