NEW ORLEANS (AP) -- Dallas Cowboys linebacker Sean Lee has been diagnosed with a concussion and ruled out for the remainder of Sunday night's game against the New Orleans Saints.

Kick returner and running back Lance Dunbar has been helped off the field with an apparent knee injury.

Lee is one of Dallas' top defensive players. He was named NFC defensive player of the week after a Week 2 victory over Philadelphia in which he was in on 14 tackles and intercepted a pass. His last tackle on Sunday night came when he helped bring down tight end Ben Watson on the Dallas 3 late in the first quarter.

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Dunbar, a New Orleans native, appeared to have twisted his knee returning the kickoff to open the second half.