TUCSON, Ariz. — On three occasions in the first half Saturday, Oregon’s sputtering offense handed Arizona some pretty nice scoring opportunities.

A fumble that put Arizona at the Oregon 21. An interception that Arizona recovered at midfield. And a blocked punt that Arizona picked up and advanced to just six yards shy of the goal line.

Yet the Ducks’ defense mitigated each gaffe, holding the Wildcats to field goals each time.

After the third field goal, when Arizona failed to punch it in from six yards out because two rushes were held to 2 yards each and quarterback Khalil Tate missed a third down pass, Oregon trailed 16-0.

It felt like it could have been 20-0. Or maybe 24-0. At least.

It felt like the sort of lost opportunity that comes back to haunt a team that fails to take better advantage. And after Oregon scored its first touchdown on its next possession, with Justin Herbert topping it by rushing for a 2-point conversion, Arizona had every reason to wonder if it might play out exactly that way.

“I thought the defense did a really good job of giving us an opportunity to change the momentum,” Oregon coach Mario Cristobal said. “I felt like it was coming, especially after the touchdown with the 2-point conversion.”

Suddenly, at that point, the Ducks weren’t down by 24 but trailing just 16-8 with 9:17 left in the first quarter.

Oregon had a life line. There was plenty of time to come back.

But it never happened.

Oregon’s offense continued to struggle all night and, eventually, its shorthanded defense couldn’t keep up. While Thomas Graham Jr. briefly gave Oregon some hope by intercepting Arizona quarterback Khalil Tate on the Wildcats’ first possession after halftime, Arizona outscored Oregon 14-0 in the third quarter to take a commanding 37-8 lead.

Any hope proved false, even though defensive lineman Gary Baker indicated he never thought of it that way.

“The momentum just goes back and forth, just like it did last week” against Washington State, Baker said.

The defense had excuses, however. It was playing mostly without three starters: Lineman Austin Faoliu, and linebackers La’Mar Winston Jr. and Kaulana Apelu.

Baker started for Faoliu, who has a lower leg injury, at defensive end, while Sampson Niu started for Apelu at inside linebacker and true freshman Adrian Jackson started for Winston at outside linebacker. Winston did not appear in the first half and only made a limited appearance because of what Cristobal said was a violation of team rules.

Apelu did not practice due to injury after leading Oregon with 14 tackles at Washington State, and also made only a limited appearance Saturday.

“Lana was obviously hobbled,” Cristobal said. “He wasn’t ready to play. We’ve got to do a better job of helping our team be able to overcome those injuries.”

But instead, while their defensive front struggled with absences, the Ducks did little to help elsewhere.

Especially in a defensive secondary that Tate attacked immediately. It was unclear entering the game if Tate would play because of his season-long ankle injury, but Tate started and wasted no time going deep into the Ducks’ secondary.

It was so bad, in fact that even Oregon’s strong rushing defense wilted. Oregon entered the game ranked second in the Pac-12 in rushing defense, allowing just 116.3 yards per game, and their 3.23 yards allowed per rush was 14th nationally.

But Arizona collected 276 yards on 51 carries, an average of 5.1 per carry.