Arizona Cardinals quarterback Kurt Warner left Sunday's game after taking a blow to the head in the second quarter, and the team said his return was questionable.

Warner was in uniform but on the sidelines for the start of the second half as Matt Leinart took over against the hometown St. Louis Rams and led the Cardinals to a 21-13 win.

Warner was 15-for-19 for 203 yards and two touchdowns, helping the Cardinals take a 21-3 lead. It was unclear when Warner was injured although he took a hard hit from safety O.J. Atogwe during a blitz on his last drive.

Warner, a two-time NFL MVP with the Rams, was facing his old team for the seventh time since joining the Cardinals in 2005. Leinart replaced him late in the second quarter.