STANFORD (AP) — The toughest test of the year for Stanford’s defense just got a whole lot tougher.

Fifth-year senior defensive end and co-captain Ben Gardner is out for the season with a left pectoral injury, handing the sixth-ranked Cardinal (7-1, 5-1, Pac-12) a major blow before facing No. 2 Oregon (8-0, 5-0) on Nov. 7. Stanford coach David Shaw said Gardner will undergo surgery to repair the damaged muscle.

Shaw said “there’s a chance” that fellow starting defensive end Henry Anderson could return against the Ducks but he will make the final decision after Anderson practices this weekend, which both teams have off.