TUCSON — On the brink of a breakthrough win, Stanford instead suffered a crushing loss.
So close to a bowl bid, the Cardinal now has its work cut out.
Unstoppable for three quarters, it couldn't make big plays in the fourth.
"This is the toughest loss you can be a part of," coach Jim Harbaugh said after a 43-38 come-from-ahead defeat to Arizona before an announced crowd of 53,479 at Arizona Stadium.
"We have to find a way to bounce back, but there's no question it hurts."
Stanford led 38-29 early in the fourth quarter, then watched Arizona grab a five-point lead on long touchdowns runs by tailbacks Greg Nwoko and Nic Grigsby.
The Cardinal's final drive ended 17 yards from the end zone, when Andrew Luck's fourth-down pass fell incomplete.
"It's heartbreaking," Luck said. "I've lost a lot of games in a lot of sports, but this stinks the most."
The loss makes November meaningful, but not the way Stanford had hoped. Instead of being a part of the Rose Bowl race, the Cardinal (4-3, 3-2 Pacific-10) now must scratch and claw for the two wins it needs to become bowl eligible.
The easiest path to the postseason would be to defeat struggling Arizona State at home next weekend, then win one of its final four — a brutal stretch that features Oregon, USC, Cal and Notre Dame.
The task would have been much simpler if the Cardinal had taken advantage of a brilliant game plan by Harbaugh and superb execution by Luck, who completed 21 of 35 passes for 423 yards and three touchdowns. (His yardage total is the third-highest in school history.) But the Cardinal was undone by a defense that yielded 553 yards and by receivers Chris Owusu and Doug Baldwin, who dropped several crucial passes in the fourth quarter.
"We are going to go back and re-evaluate and figure out what's going on," tailback Toby Gerhart said. "There comes a point where you have to stop making some of these mistakes. It's going to be a tough film to watch on Monday."
Stanford moved the ball at will for three quarters and stopped Arizona just enough to hold a nine-point lead early in the fourth. But after Nate Whitaker missed a 36-yard field-goal try, everything unraveled for the Cardinal.
The Wildcats cut the deficit to two points when Nwoko broke free for a 43-yard touchdown in which he went untouched up the middle of Stanford's defense.
The Cardinal had a chance to extend its lead midway through the quarter. But on fourth-and-two from Arizona's 8-yard line, Harbaugh passed on a field goal and went for the first down.
The options were limited because Gerhart had hobbled off the field with what he called a "tweaked" ankle. So Harbaugh called for a pass. Luck turned and threw a quick strike to Owusu on the left side that would have been good for the first down, except Owusu dropped it.
"We just didn't make the play," Gerhart said. "That was kind of our motto for this game: 'Make the play.' And we obviously didn't do that."
The Wildcats made Stanford pay. Quarterback Nick Foles, who matched Luck pass for pass, hit receiver Juron Criner for 37 yards to midfield. But the Wildcats sputtered and faced third-and-17 with just over three minutes remaining.
Then came the play of the game: A draw to Grigsby, who sliced through the surprised Stanford defense, cut past cornerback Kris Evans and raced 57 yards for the go-ahead touchdown with 2:57 left.
Luck quickly moved the Cardinal to Arizona's 12, where it faced second-and-five with 38 seconds remaining. After a timeout, Stanford was called for a delay-of-game penalty. Then Baldwin dropped a pass, Luck threw incomplete twice, and Arizona's celebration began.