PULLMAN, Wash. — Mark Sanchez became the first USC quarterback to throw five touchdown passes in a half and the No. 6 Trojans breezed this time as a huge favorite, beating Washington State 69-0 today.

It was the largest shutout victory for USC (5-1, 3-1 Pac-10) since a 69-0 win over Montana in 1931, and the Trojans were showing signs of mercy late in the first half.

USC's defense, ranked first in the nation coming in by allowing just 9.4 points per game, ended the Cougars' streak of scoring at 280 games dating to Sept. 15, 1984, when Ohio State beat Washington State 44-0. That scoring streak was second-longest in the nation to Michigan's 295 games.

The Cougars absorbed their largest margin of defeat since they began playing in 1894.

Patrick Turner and Ronald Johnson each caught two of Sanchez's scoring throws, freshman Broderick Green rushed for 121 yards and two touchdowns and C.J. Gable ran for 109 yards and three more scores. The Trojans have won their last three games by a combined 141-10 since a stunning loss at Oregon State on Sept. 25 cost them their No. 1 ranking.

Now they sit ready to rejoin the BCS championship chase. Not that this was the best barometer of their worthiness.

Washington State (1-7, 0-5) has allowed 66, 63, 66 and now 69 in four of their conference losses. The Cougars, whose only win is against Portland State of the Championship Subdivision, have been outscored 385-111 this season. That's on track to break the Pac-10 record for most points allowed in a season, 469 by Oregon State in 1981.

On offense, they never crossed midfield. They protected quarterback Kevin Lopina from getting hit and tried to shorten this rout by snapping directly to running backs and even wide receivers in passing situations. Lopina completed six of nine passes for 28 yards — WSU's lowest air output since 1975 — with one interception. He hit the ground twice in his return from a broken bone in his back.

Washington State had four first downs. They didn't advance past their own 38-yard line until the third quarter — when third-stringer Logwone Mitz lost a fumble at the WSU 40 at the end of a run.

The dispirited home fans gave a mocking standing ovation 2:30 left in the first quarter when Lopina found Jeshua Anderson for a 10-yard completion. It Washington State's only first down of the half.

The Trojans outgained Washington State 408-17 in the first half and 625-116 for the game.

Sanchez tied the school record of five scoring throws for a game — shared with Rodney Peete, Carson Palmer and Matt Leinart — with 4:51 still remaining in the second quarter. Tight end Anthony McCoy turned a 10-yard pass into a 21-yard touchdown by spinning away from a hit by Xavier Hicks and then turning past two Cougars to the end zone. That made it 41-0, the Trojans' largest output in a half since they scored 44 against Stanford in 2005.

USC could have had more than that at halftime, but coach Pete Carroll had the offense run to use the final 35 seconds of the opening half, leaving the ball at the Cougars 10 as time expired.

Throughout the second half Carroll stayed primarily with basic plays. Backup quarterback Mitch Mustain handed off to USC's running backs, except tailback Joe McKnight. He watched on the sidelines in a sweat suit with a toe injury one week after gaining a career-high 143 yards rushing in a 28-0 win over Arizona State.

Sanchez, the Pac-10's leader in passing efficiency finished 15-for-20 with 253 yards passing in just 2½ quarters. He has 19 touchdown passes and six interceptions this season.