Will two near comebacks come back to haunt USC?

Colorado was looking for a big play Saturday, the kind that could somehow swing a lopsided game against USC into one in which a miracle could occur.

So coach Mike MacIntyre sold out to try to block USC’s punt.

The outcome was not a surprise. Colorado stormed in with eight players. USC had just three blockers. Math did the rest: The Buffaloes got their punt block. USC, which had led Colorado by 27 points 60 seconds earlier in the third quarter, was about to have its lead shaved to 13.

The Trojans would survive the scare, but for the second week in a row, they struggled to close out what could have been an easy victory. The week before, USC led Arizona by 22 points in the third quarter; the lead had completely vanished by the middle of the fourth.

“I think they started making plays,” coach Clay Helton said of Colorado. “I thought their wide receivers made a couple deep-ball plays on some double moves that caught us. We are an aggressive defense.”

But even more than by Colorado’s playmaking, the comeback was facilitated by USC breakdowns that could’ve been fatal had USC not staked itself to such a large cushion. Immediately before the punt block, a blown assignment in the secondary gave Colorado a wide-open 79-yard touchdown pass to Juwann Winfree.

In the fourth quarter, Winfree blew past cornerback Jack Jones for a 57-yard touchdown reception. And Colorado nearly made it a one-possession game late before its final drive stalled inside USC’s 10-yard line.

“Really three plays allowed them to score points in that game,” Helton said.

He defended USC’s play by noting that Colorado never had the opportunity to tie the score or take the lead on one play.

“When you look at it, we were three scores up at halftime, and they were able to cut it to a two-score ballgame and really never cut it anywhere closer to that,” Helton said. “We kept it to two scores for the rest of the game. They scored, we scored, but never got it to a one-score ballgame.”

The uninspired finishes did not stop USC from winning the Pac-12 Conference South, but they could end up hurting USC’s long shot playoff dreams.

Other two-loss hopefuls have resumes dotted with blowouts. Auburn defeated Mississippi State by 39 points and Georgia by 23. Ohio State defeated Michigan State by 45 on Saturday.

Pac-12 foe scenarios

USC clinched the chance to play for the Pac-12 championship almost three full weeks before the game.

It will take two more weeks until USC finds out who its opponent will be. The three possible teams are Stanford, Washington State and Washington.

Washington State’s path in is simplest: defeat Washington, and it’s in.

Stanford needs a win against California this week combined with a Washington State loss to Washington in two weeks.

Washington requires more help. It needs a win over Utah this week, a win over Washington State the following week and a Stanford loss to California.

Bye bye to no bye

USC’s appearance in the Pac-12 championship game gives the team a bye week at a fortuitous time.

A quirk of the schedule left the Trojans with no regular-season bye. Its first week off will be after this week’s game against UCLA. It would turn into a bye only if USC won the Pac-12 South.

Several players noted throughout the season, when USC was leveled continuously by injuries, that the bye week would’ve been nice. Now, though, USC will enter the championship game with an advantage.

“We could’ve used a bye about halfway through the season, probably right after Washington State with the injuries we had,” Helton said. “But like I said earlier in the year and in the beginning, I’m a glass half-full guy. And I said that if we got our job done, then our bye would come after the 12th game, and with good fortune we’ve been able to do our job, and now we get it.”

Quick hits

USC’s game against UCLA on Saturday will kick off at 5 p.m. and will air on ABC. … There were no new USC injuries after Saturday’s game for the first time all season. “Probably our healthiest game,” Helton said. … On Twitter on Saturday, former USC quarterback Max Browne shared this story about Ajene Harris after Harris made two interceptions: “Before he got to USC, [Harris] used to ride the bus from his home into campus to throw routes with me. Glad the world is seeing his work pay off.”

zach.helfand@latimes.com

Follow Zach Helfand on Twitter @zhelfand