SAN DIEGO — There was the strained groin in 2004, the lingering rib injury in 2005, a jaw injury in 2006, the knee injury in last year's playoffs and then his jammed right big toe earlier this season.

Now there's the groin injury that's dogging LaDainian Tomlinson to the point that he might have to sit out the San Diego Chargers' playoff game at Pittsburgh on Sunday.

The star running back isn't sure if a week's worth of treatment and rest is going to be enough to allow him to play.

"I don't know. It's tough," Tomlinson said after the Chargers' light workout on Monday. "This is a tough injury. I would probably venture to say it's probably the toughest of my career. We'll see what happens."

The injury, sustained in the final regular-season game, robbed Tomlinson of his burst and shiftiness to the point that he came out of Saturday night's 23-17 overtime wild-card win over the Indianapolis Colts after scoring on a 3-yard run early in the second quarter.

Speedy little Darren Sproles took over after that. Sproles had 328 all-purpose yards, including the winning 22-yard touchdown run.

The Chargers say Tomlinson has a strained groin. There have been reports he has a detached tendon.

L.T. chose not to clarify the situation.

"I won't because it is a medical issue and different doctors have their opinions," he said. "I'll leave it at that."

If a week's worth of treatment and strengthening exercise go well, Tomlinson could test the groin before the game on Sunday, as he did before Saturday night's game. But he also said there's a chance he could be ruled out of the game before Sunday arrives.

"I'm pretty sure at some point I'll try it to see where I am. Then we'll see what happens. That's why we're leaving it as day-to-day and just see how it reacts."

Tomlinson hurt his left knee in last year's divisional-round upset win at Indianapolis, then aggravated it early in the AFC championship game at New England. He stood on the sideline for the final 3› quarters of the 21-12 loss to the Patriots.

Tomlinson had the lowest output of his brilliant eight-year career just two seasons after winning the league MVP award, setting records with 31 touchdowns and 186 points, and winning the first of two straight rushing titles.

He said he felt nervous standing on the sideline Saturday night.

"I think the thing that's toughest to me is knowing I have no control. I can't make any plays out there for the team. That's the hardest thing for me. I haven't been in that position too much where I just had to stand over there and watch."

Tomlinson said he was proud of Sproles.

"Anytime a guy gets an opportunity, you want him to do well, especially when it's one of your guys and you're all out for the same goal. We always talk about how we're going to need each other and it's not more important than it is now. We definitely need him."

Besides Sproles, the Chargers have Michael Bennett, a late-season pickup, and rookie Jacob Hester.