Injury-plagued Colorado defense takes “next man up” to extreme in Arizona loss

BOULDER» Just a few months ago, Sam Noyer started summer camp in a battle for the third quarterback spot on Colorado’s depth chart.

At the start of the second half Saturday at Folsom Field, he found himself in the Buffs’ secondary at free safety.

Such was the state of a depleted CU defense forced to take “next man up” to the extreme after safety Mikial Onu and defensive lineman Jalen Sami were knocked out of the game against Arizona by halftime — the fourth and fifth opening-night starters to go down with injuries this season.

“Injuries are a part of the game.`next man up’ is not a cliche. It’s what’s required,” Buffs coach Mel Tucker said. “We had enough guys to finish the game. We were able to put 11 out there on every snap, so there’s really no excuse.”

Excuses or not, Arizona and its quarterback, Khalil Tate, took advantage in their 35-30 win, scoring touchdowns on three of their first five drives of the second half.

Isaiah Lewis eventually spelled Noyer at free safety, but the Wildcats kept marching, with Nathan Tilford’s 5-yard plunge putting them ahead for good with 6:51 to go.

“Three weeks ago, I’d say it’s tough (playing with so many new guys),” said linebacker Nate Landman, who recorded his first tackle for loss of the season Saturday. “Now I don’t really see it as an obstacle, just because those guys have so much coaching under them over these weeks and having a bye week. I trust every one of those guys.”

Onu was no small loss for the Buffs. The SMU graduate transfer’s interception of Tate late in the second quarter — Onu’s fourth of the season — preceded a 38-yard reverse touchdown pass from K.D. Nixon to Dimitri Stanley that gave the Buffs their first lead of the game, 13-7.

Onu appeared to strain something on the first play of Arizona’s next offensive series — a 75-yard bomb from Tate to Cedric Peterson that ended with the starting free safety clutching his side.

In addition to Onu’s injury, the Buffs also lost Sami at nose tackle late in the first half to an injured right knee.

Those were big blows for a defense that was already down senior defensive end Mustafa Johnson, free safety Aaron Maddox and cornerback Chris Miller.

And with Arizona gaining 272 of its 487 total yards in the final two quarters — 219 of which came through the air — it left CU without answers ahead of a two-game road swing against two of the Pac-12’s most explosive offenses in Oregon and Washington State.

“We are hoping to get some guys back. We will have to see how the week unfolds,” Tucker said.

Matt Schubert: 303-954-1829, mschubert@denverpost.com or @Mattdschubert