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 victory still felt like one big breakthrough for the maverick coach and his Cougars.
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 victory against 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.
"You can't worry about that," Kiffin said of the chants. "I think I heard those before the game started, so I'm used to it. ... When you don't play well, it falls on the head coach. We obviously weren't well-prepared on offense."
Washington State's defense mostly shut down USC's cautious offensive game plan, and it scored the Cougars' only touchdown when Cody Kessler threw behind a receiver.
Tre Madden rushed for 151 yards and Marqise Lee had seven catches for just 27 yards for the Trojans, whose inept offensive performance had fans loudly booing and chanting even before USC fell behind. They really let Kiffin have it when he ran up the tunnel alone after his halftime interview.
Kiffin's two-quarterback offense managed only 193 yards on 63 plays, with no pass completion longer than 8 yards. The Trojans also missed a field goal and had another blocked after scoring their only touchdown on an early 22-yard drive set up by their dominant defense, which has nearly shut out two successive opponents.
Kessler went 8 of 13 for 41 yards and rushed for a 4-yard TD in his second successive start at quarterback for the Trojans. Wittek took over at halftime and went 3 of 8 for 13 yards, struggling to hit open receivers.
"That's just fans being fans," Lee said. "They aren't seeing what they want. They're not out there and seeing what's going on. ... It takes time. We don't have [Matt] Barkley any more. New quarterbacks are coming in. They have to understand it takes time."
Washington State's offense moved the ball well early on, but River Cracraft dropped a sure touchdown pass behind him in the end zone on the Cougars' second drive. Two plays later, Torin Harris picked off Halliday's forced pass into the end zone, ending a 74-yard drive with a touchback.
Washington State drove into USC territory again, but Morgan Breslin created havoc on three straight plays -- drawing a holding penalty, sacking Halliday and helping George Uko to force a fumble recovered by Devon Kennard, who returned it to the Cougars 22.
The Trojans converted a fourth-and-1 with a direct snap to Madden before Kessler scored on a 4-yard bootleg 9:59 before halftime.
Wittek took over at halftime, and a drive with eight consecutive runs got USC into field goal range -- but Kalafitoni Pole blocked Andre Heidari's 32-yard attempt. Heidari missed a 43-yard field goal attempt to end the Trojans' next drive, and the Cougars stopped Lee just short of the marker on fourth down at their own 29 with 9:03 to play.
After the Cougars took over at their 20 with 6:18 left, two plays went nowhere before Williams eluded several tacklers and made it 49 yards down the Washington State sideline.
The Trojans played without injured tailbacks Silas Redd and D.J. Morgan and cornerback Anthony Brown. Morgan Breslin returned to USC's starting lineup after missing the season opener with an injury, moving into his linebacker spot in the Trojans' new 5-2 defense after excelling as a defensive lineman last season.