Murphy says he got hurt when he was kneed in the helmet by teammate Nnamdi Asomugha during practice Friday. He has a bad headache and missed practice Saturday.
Coach Tom Cable says Murphy will not return until he passes a series of tests that shows he has recovered. Murphy says he has never had a concussion before.
Murphy is being counted on heavily in his second year in the NFL. He led all Raiders wideouts with 34 catches for 521 yards and four touchdowns as a rookie last season.