Next for USC: The surprising Colorado Buffaloes stand alone atop the Pac-12 South

Colorado Coach Mike MacIntyre was still half out of breath by the time he reached the postgame news conference Saturday.

And why not? The Buffaloes had just dismantled Oregon State, 47-6, a week after shocking Oregon on the road. It was official: Colorado had its first Pac-12 Conference winning streak since joining the conference in 2011.

At one point in the news conference, MacIntyre looked around, then interrupted a question to remark, “These lights are bright! We don’t usually have these lights. What’s going on?”

These are heady times for Colorado, USC’s surprisingly ascendant next opponent. The Buffaloes are ranked in the Associated Press top 25 for the first time since 2005, at No. 21. They now stand alone atop the Pac-12 South Division standings.

Their surge gives Saturday’s game at the Coliseum added significance. Colorado has an even more potent offense than Arizona State, a unit USC Coach Clay Helton publicly fretted over before last week’s game.

Colorado ranks ninth in the nation in total offense, averaging more than 531 yards per game; Arizona State had averaged 508 before last week.

“Their skill level across the board is excellent on the offensive side of the football,” Helton said in a teleconference with reporters Sunday.

Colorado ranks in the top 10 nationally in plays of 30 yards or more. It has had seven plays go for 50 yards or more, tying for fifth.

Starting quarterback Sefo Liufau has missed the past two games with an ankle injury, though backup Steven Montez has not been much of a downgrade. MacIntyre told reporters that Liufau participated in practice on Monday.

Both quarterbacks, Helton said, “look for the deep ball.”

Unlike Arizona State, Colorado pairs its powerful offense with a capable defense, which ranks ninth in passing defense.

Helton laughed that “it’s just another week in the Pac-12.”

It was a compliment — one that no one could tag to Colorado in years past.

Asked about the significance of his team’s latest win, McIntyre said, “I think it proves we’re legitimate, maybe. That we can do it.

“Everyone kept telling me all week, ‘Are they gonna have a letdown, are they gonna have a letdown, are they gonna have a letdown?’ ”

They haven’t yet.

Early gamble

Helton’s attempt early in the Arizona State game on fourth-down-and-two from USC’s 42-yard line was an usual one.

Helton has said he prefers to be aggressive on fourth downs, but he was coming off two games, against Stanford and Utah, that included controversial decisions to punt late in the game.

The attempt against Arizona State was unsuccessful. And, Helton said, it doesn’t reflect any shift in philosophy.

“To be honest with you, I was scared to death of their offense and how many points they can put up,” Helton said.

Quick hits

MacIntyre offered an interesting assessment of USC’s offensive success over the past two games. “They basically completely changed their offense in the last game and a half,” MacIntyre told reporters Monday. “They’re basically a spread football team now, in a way.” … USC’s game on Oct. 15 at Arizona has been scheduled for 12:30 p.m. and will air on Channel 11. It will be the first daytime home game this season for Arizona, which shuns early-season day games to avoid scorching temperatures.

zach.helfand@latimes.com

Twitter: @zhelfand