SAN DIEGO (AP) Antonio Gates did the crime and served the time.

Although he still hasn't fessed up to what he tested positive for that got him suspended for four games, the San Diego Chargers' star tight end took responsibility, had a verbal spat with Hall of Famer Shannon Sharpe, and is now ready to play football.

Gates returns to action Monday night when the Chargers (2-2) face the Pittsburgh Steelers (2-2), who will be led by Mike Vick in place of the injured Ben Roethlisberger.

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''I never came back with the anticipation this is about Antonio Gates,'' he said. ''I came back with the anticipation of just being able to contribute to what the San Diego Chargers are trying to do, collectively, to win a football game. I wouldn't dare put that much pressure on myself.''

Gates needs one touchdown catch for 100 in his Hall of Fame-caliber career.

Quarterback Philip Rivers has had plenty of other targets to throw to during Gates' absence, including fellow tight ends Ladarius Green and John Philips, but few are better inside the 20-yard line. Rivers has thrown 72 touchdown passes to Gates, the most from a QB to a tight end in NFL history.

''Whatever it is the coordinator wants, whatever position, whatever role he wants me to be in, just try to do that to the best of my ability and things will be fine,'' Gates said. ''Just find a way to get a win. That's the most important thing.''

Gates was probably the last guy anyone expected to violate the NFL's policy on performance enhancing drugs. His squeaky clean image off the field was as sure a thing as his ability to pivot and catch a pass from Rivers, even in double coverage.

His suspension was announced in early July. The penalty was four games without pay.

Gates hasn't shined any light on what he tested positive for, other than to say that his testosterone level was high. On the opening day of training camp, he said a big part of his routine is taking naturopathic medicine, ''just taking certain things for my cleansing, my kidney, liver, making sure my sugar level is right.''

Gates took responsibility and said he let the team down.

''I think you have to be more aware,'' he said. ''That's the lesson you learn. You have to understand there's a multitude of things you can't have, despite whatever reason, whatever way you want to rationalize it as a player; you didn't know, somebody didn't tell you. It doesn't matter. You're accountable for what you put in your body ... no matter what it is, I'm responsible for it.''

Some other things to know about Steelers-Chargers:

WAR OR WORDS: Sharpe said in early July he thought Gates' suspension ''calls into question everything'' Gates has ever accomplished. Sharpe said Gates ''cheated himself, and he cheated the game.''

Gates said he didn't try to reach out to Sharpe after hearing the comments.

''No I didn't. We played against each other so it wasn't like he was a teammate of mine or we were the best of friends. But we do know each other and it was always competitive in terms of who was the better tight end. We joked about it and we laughed about it. So I guess if he can find a way to tarnish some things, I'm sure he probably would.''

The verbal jesting continued Friday, first with Sharpe taking more shots on his radio show and then Gates responding in an interview on a San Diego station.

Now it's on to football.

NO LEBEAU: The Steelers are without defensive coordinator Dick LeBeau, who jumped to the Tennessee Titans. Pittsburgh ranks 12th in pass defense, 18th against the rush and 13th overall under new coordinator Keith Butler.

''The coordinator has changed but the style of football is the same,'' Gates said. ''That defense sets the tone. I can't say enough about their front seven. It's a big challenge for us offensively to go in and try to protect our home field.''

NO TDS: Chargers first-round draft pick Melvin Gordon has more TV commercials than touchdowns. Four games in and the former Wisconsin running back has yet to find the end zone. ''It's a long season,'' offensive coordinator Frank Reich said. ''He certainly is a talented guy. We've had opportunities and he's been close to breaking a couple.

''You just learn in this business to be patient and trust what you are doing and the people you are doing it with. He has all the tools to score a bunch of touchdowns and that is what we are hoping for in the coming weeks.''

VICK, NOT BIG BEN: Roethlisberger was injured in Week 3 and Vick, who was signed just before the season when backup Bruce Gradkowski was sidelined for the season, too his place in a loss to Baltimore. Vick struggled in the second half and overtime against the Ravens and now faces a defense vulnerable to the run. Look for All-Pro RB Le'Veon Bell to get plenty of work to take the onus off Vick.

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