Saints cornerback Keenan Lewis out with a quad injury against 49ers _lowres

San Francisco 49ers wide receiver Anquan Boldin (81) pulls in a touchdown reception in front of New Orleans Saints cornerback Keenan Lewis (28) in the first half of an NFL football game in New Orleans, Sunday, Nov. 9, 2014. (AP Photo/Bill Haber)

Starting Saints cornerback Keenan Lewis is out for the rest of Sunday's game against San Francisco, the team announced at halftime.

Lewis was injured late in the second half while defending a pass thrown to 49ers tight end Vernon Davis.

Lewis, the Saints' most consistent defensive back in passing situations, is being replaced by Patrick Robinson.

The Saints enter the third quarter trailing 21-10.