Running back Darren McFadden suffered a high ankle sprain on his first carry of Sunday's 42-32 loss to the Tampa Bay Buccaneers, and the Oakland Raiders running back played through it before aggravating the injury later, a league source told ESPN NFL Insider Adam Schefter.
McFadden is scheduled to undergo an MRI on Monday, the source told Schefter, and is considered week to week.
The Raiders said X-rays on McFadden's ankle were negative.
Oakland's leading rusher went to the locker room late in the second quarter. He ran for no gain up the middle on his final carry, but it was unclear how he sprained the ankle. McFadden finished with seven carries for 17 yards.
Making matters worse for Oakland, backup Mike Goodson injured his right ankle on a 12-yard catch in the fourth quarter and did not return.
Raiders safety Matt Giordano also injured his hamstring when he missed a tackle on Doug Martin at the end of the running back's 67-yard touchdown run late in the third quarter. Giordano walked off the field with the help of team trainers and did not return.
Defensive tackle Desmond Bryant was taken to the hospital because of a fast heartbeat.
The Raiders say Bryant was transported to Eden Medical Center in Castro Valley as a precaution at the beginning of the second half. No further details were announced.
The Raiders drafted McFadden fourth overall out of Arkansas in 2008. He has proven to be one of the NFL's most dangerous running backs the past two seasons when healthy.
But the problem for McFadden and the Raiders has been staying on the field. He missed 19 games in his first four seasons with foot, toe, shoulder, knee and hamstring injuries.
Information from ESPN NFL Insider Adam Schefter and The Associated Press was used in this report.