DENVER (AP) – The NFL is investigating whether Denver coach Mike Shanahan broke a rule when he lied about quarterback Jake Plummer’s injury in a victory at San Diego.

The Broncos initially said Plummer sustained a concussion in the second quarter of Sunday’s 37-13 win over the Chargers. After the game, Shanahan announced his quarterback had a separated right shoulder.

He said he lied because the Chargers would have had an advantage if backup Steve Beuerlein got hurt and Plummer had to re-enter the game. Denver carries just two quarterbacks.

NFL spokesman Greg Aiello said the league expects injury information to be as accurate as possible.

Rules for reporting in-game injuries aren’t as specific as pregame injuries, which require a designation – out, doubtful, questionable and probable.

Shanahan could be fined if the league determines a rule was broken.

Plummer was injured in the second quarter after throwing three touchdown passes. He finished 9-of-13 for 94 yards, with no interceptions.

Shanahan said Monday the quarterback could have gone in and played the rest of the game.

“But we wouldn’t have wanted to subject him to throwing the football because he couldn’t – it was quite sore,” Shanahan said. “We didn’t want the opposition to know that he couldn’t throw the football or they’d stack the line of scrimmage so we couldn’t run the football.”

“To share with somebody that Jake has a separated shoulder and could not throw and our quarterback goes down, we have a good chance to lose the football game,” he added.

The coach said he wasn’t about to say anything that could help the Chargers.

“If somebody can game-plan me at halftime what we’re going to do against the opposition, that’s ludicrous,” Shanahan said. “Now, if the rules change and they put something in, then I’ll have to change. Right now, at least in my judgment, there’s no rules like that.”

Broncos tight end Shannon Sharpe questions the authority of the NFL in such cases.

“I think sometimes the NFL takes it too far,” he said. “They take advantage of the powers that they have. For all intents and purposes, they are the governing body and they don’t have to answer to anybody.”

AP-ES-09-15-03 1716EDT