SEATTLE -- And then there was one.

Just hours after No. 2 Clemson fell from the ranks of the unbeaten and right before No. 3 Michigan lost to Iowa, No. 4 Washington's undefeated season also came crashing down thanks largely to a player, USC redshirt quarterback Sam Darnold, who was an anonymous backup two months ago.

No. 20 USC's 26-13 win creates both chaos in the College Football Playoff picture and provides a boost for the Trojans' Pac-12 title chances.

Earlier this week, USC safety Chris Hawkins was asked where he thought Washington quarterback Jake Browning stacked up against others in the Pac-12.

He thought about it for a second, and then answered.

"I haven't played them all, so I wouldn't be able to tell you that," he said. "But I know we got the best, though."

Sam Darnold and USC got to celebrate a big win over No. 4 Washington. Joe Nicholson/USA TODAY Sports

Anyone want to argue with him?

Browning came into the game as the Pac-12's most likely Heisman candidate, but by halftime it was clear he was the second-best quarterback on the field.

Since taking over as the starter in the fourth game of the season, Darnold has been spectacular. He has been viewed as the primary reason for the Trojans' reversal of fortune following their 1-3 start, but some pointed to the quality of the defenses he has carved up over the last month and wanted to see if he could do it against a more formidable defense. Before a loud, sold-out crowd of 72,362, the largest since Husky Stadium was renovated in 2013, that's what he got.

Darnold responded with arguably his best performance of the season.

He finished 23-of-33 for 287 yards with two touchdowns and two interceptions, which doesn't compare favorably with several other performances, but the stats hardly tell the full story.

Considering the significance of the game, the venue, the quality of the opponent, what Darnold did on Saturday night was truly special. He was calm in the pocket, bought time when he needed to and continuously found open receivers. Those are things he has done for weeks, but they resonated differently against the likes of Arizona, California and Oregon.

It's fair to wonder where he would fit into the Heisman discussion, if Darnold had opened the season as the Trojans' starter.

But Saturday's win wasn’t just about Darnold. He was the obvious star, but the defense also turned in its best showing of the season. The Trojans limited Washington, the Pac-12's top-ranked rushing offense, to just 17 yards on the ground and forced Browning into his worst performance of the season (17-for-36, 259 yards, one touchdown, two interceptions).

USC would not have been mathematically eliminated from the Pac-12 South race with a loss to Washington, but it would have created the need for a string of extremely unlikely outcomes. Now the Trojans have a manageable path to a second consecutive Pac-12 title game, though. They still need help -- Colorado (5-1) has one fewer loss, pending tonight's game against Arizona, and Utah (5-2) holds a head-to-head tiebreaker -- but the odds are much better than when the day began. One likely scenario would be for Colorado to lose to Washington State next week, then beat Utah in the regular-season finale.

For Washington, there is still a path to the playoff, but it's no longer as clearly defined. All the Huskies had to do was win out and they were likely in, no questions asked. Obviously, that's easier said than done, but now there are far more factors in play. The Huskies will still win the Pac-12 North with wins against Arizona State and Washington State the next two weeks. If they go on to win the Pac-12 title game after that -- maybe in a rematch against USC? -- they would still have a strong case to be among the four-team field.