EUGENE, Ore. - Dennis Dixon will have surgery on the left knee that buckled early in second-ranked Oregon's upset loss to Arizona, costing the Ducks a shot at the national championship and likely his hopes for the Heisman Trophy.

The quarterback tore his anterior cruciate ligament during Oregon's Nov. 3 victory over Arizona State, according to coach Mike Bellotti, but he had rested it and felt like he was ready to play Thursday night against the Wildcats.

Dixon will miss the rest of this season.

The versatile Dixon was one of the front-runners for the coveted Heisman award after he put the Ducks in line for the national title. Oregon had started the season unranked, and was picked to finish sixth in the Pacific-10 Conference.

Thursday night's 34-24 loss to the unranked Wildcats knocked the Ducks (8-2, 5-2) out of the national title picture. Oregon was ranked behind LSU and ahead of Oklahoma and undefeated Kansas.

Dixon's left knee crumbled as he tried to plant on an option carry with about 5 minutes to go in the first quarter against Arizona (5-6, 4-4).

(Copyright 2007 by The Associated Press. All Rights Reserved.)