PULLMAN - Backup quarterback Marshall Lobbestael rescued Washington State twice on Saturday.

Lobbestael started in place of Jeff Tuel, who was suffering from a stomach virus, and directed the Cougars to two quick touchdowns.

Tuel felt well enough to go in, but only lasted one series before fracturing his left clavicle.

It was Lobbestael to the rescue again as Washington State rolled to a 64-21 win against overmatched Idaho State of the FCS on Saturday.

"I was ready to go when coach said Jeff was not feeling very good," said Lobbestael, a former starter who didn't figure to play much his senior year. He completed 14 of 19 passes for 230 yards and two touchdowns and was not intercepted as he led to the Cougars to a 40-0 halftime lead.

Tuel should be out four to six weeks, coach Paul Wulff said.

"It's on his non-throwing shoulder," Wulff said. "In the meantime, we do have the luxury of a fifth-year senior in Marshall Lobbestael to go to."

Wulff said the coaching staff never considered sitting Tuel the entire game and decided to put him in after he responded well to treatment for the stomach ailment.

"He was our leader," Wulff said.

Lobbestael completed his first nine passes and directed a Cougar offense that produced 590 total years. That included 289 rushing yards, with 88 from freshman Marcus Mason and 64 from Rickey Galvin. Marquess Wilson caught four passes for 91 yards for WSU.

Linebacker Alex Hoffman-Ellis, who returned an interception for a touchdown, said it was too soon to get really excited about WSU's play, especially against an outclassed opponent.

"Throughout the year we'll be tested and tested," he said.

Washington State scored on its first four possessions against the Bengals, jumping to a 23-0 lead after the first quarter. Idaho State lost its 11th game in a row, dating to last season. The loss ruined the debut of Idaho State coach Mike Kramer, who was an assistant last season to Wulff.

"We didn't tackle the way we needed to when playing a team like Washington State," Kramer said. "Their offense is much improved."

Junior college transfer Kevin Yost, making his first start at quarterback for Idaho State, completed 32 of 45 passes for 386 yards and a touchdown. Rodrick Rumble had 10 catches for 218 yards.

This was WSU's most dominant win since beating FCS Portland State 48-9 in 2008. Idaho State was 1-10 last season.

The game was a chance for Washington State to show it is improving after posting a 5-32 record in Wulff's first three seasons. Washington State has never lost to an FCS team in 16 outings.

The last time Idaho State beat a major college team was Utah State in 2000, and they have lost 15 in a row since. They have lost 28 straight road games, last winning at Northern Colorado in 2006.

Washington State took the opening kickoff and went 58 yards in five plays, with Galvin scoring on an 11-yard run. Lobbestael hit Isiah Barton on a 27-yard touchdown pass on WSU's second possession.

Tavoy Moore fumbled the ensuing kickoff and Bennett Bontemps recovered for WSU at ISU's 30. Tuel took over for Lobbestael and the Cougars settled for a 23-yard field goal by Andrew Furney and a 17-0 lead. Tuel did not start the game because of a stomach virus, and only played this one series. He was injured while being tackled on a bootleg, but stayed in the game to complete one more pass before the field goal.

Tuel, a junior, threw for 2,780 yards and 18 touchdowns last season.

Idaho State drove to WSU's 36 on the next possession, but Yost was intercepted by Ellis, who returned the ball 67 yards for a touchdown and a 23-0 WSU lead.

With Lobbestael back, WSU drove 74 yards on its next possession, with Galvin rushing the final seven for a 30-0 lead. Furney kicked a 51-yard field goal and Marquess Wilson caught a 61-yard touchdown pass for a 40-0 halftime lead. It was WSU's biggest halftime margin since they led SW Louisiana 56-0 in 1997.

After the Cougars went up 47-0, Idaho State finally scored when Jahmel Rover ran in from 3 yards to cap a 73-yard drive with 8:53 left in the third. Rover ran in a second touchdown with 4:21 left in the third to bring Idaho State within 54-14.

Mason added a 65-yard touchdown run for WSU.

It was the first time WSU has scored 60 points in a game since 1997.