LOS ANGELES -- Mike Leach couldn't stand in the Coliseum tunnel and pretend everything went according to plan for Washington State in a messy, clunky game dominated by both defenses.

With a few dozen boisterous players celebrating in the locker room behind him, this win still felt like one big breakthrough for the maverick coach and his Cougars.

Andrew Furney kicked a 41-yard field goal with 3:03 to play, and Washington State beat No. 25 Southern California 10-7 Saturday night for its first victory at the Coliseum in 13 years.

Damante Horton returned an interception 70 yards for a tying score in the final seconds of the first half for Washington State (1-1, 1-0 Pac-12), and he made the clinching interception with 2:18 to play in the Cougars' first win over the Trojans anywhere since 2002.

Washington State won without scoring an offensive touchdown. That's not normal Leach protocol, but he didn't mind at all.

"Both sides were dominating up front, and it was hard to scratch and eke something out," Leach said. "I'm proud to say we did."

Washington State celebrated with its small cheering section after the final gun while boos rained down on USC coach Lane Kiffin and a team that lost its home opener for the first time since 1997.

Neither team scored in the second half until Dom Williams took Connor Halliday's third-and-long screen pass 49 yards, winding past tacklers to the USC 30 with 5½ minutes left to set up Furney's tiebreaking kick.

"It's the start, and that's what we're taking it as," Washington State left tackle Gunnar Eklund said. "That's where it starts for Washington State University. The defense won the game for us. They stepped it up big-time, and when the offense needed to, it went down the field."

Horton then picked off Max Wittek's pass to finish off USC (1-1, 0-1), which finished the game under repeated chants of "Fire Kiffin!" from an incensed fan base. It's not exactly a signature win for Leach, but it's the ugliest moment yet for the embattled Kiffin, who calls the Trojans' plays.