Rookie Thomas Rawls already has a pair of 100-yard games this season.

Otto Greule Jr. Getty Images

Seattle Seahawks coach Pete Carroll said the team is still trying to figure out the severity of a calf injury to rookie running back Thomas Rawls.

"It's kind of a nasty calf thing he's got going on," Carroll told reporters Wednesday. "Trainers are trying to determine if it's a strain or just a bruise. He did run a little bit yesterday, been running a little bit today."

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Rawls and starting running back Marshawn Lynch were the only Seattle players who didn't practice Wednesday. Carroll said the uncertainty over Rawls' condition prompted the team to sign running back Bryce Brown on Tuesday.

Brown was released by the Buffalo Bills last month following the season opener and Carroll admitted he was unsure what the career backup can provide.

Rawls replaced an injured Lynch in Week 3 against the Chicago Bears and rushed for 104 yards on 16 carries. He had a monster game with 169 yards on 23 carries in Week 5 but has seen his playing time diminish with the return of Lynch to the starting lineup.

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