For the second straight season, Kansas State upset a highly ranked Oklahoma team. This time, the Wildcats did it against a stacked deck.

Despite trailing by three touchdowns in the second half and missing eight key players from their two-deep, Kansas State took down the No. 3 Sooners 38-35 on Saturday in Norman, Oklahoma.

"It's a big win with the circumstances we faced and some of the adversity our guys have gone through," Kansas State coach Chris Klieman said. "Excited that we fought for four quarters. I trust those guys, I believe in them; the biggest thing is they need to believe in themselves. They know we want to give them opportunities, and they made the most of them today."

The win was Kansas State's first on the road over a team ranked in the top three of The Associated Press poll. The Wildcats had lost their past 16 such games. It was also their first win as an unranked team against a top-three team in 30 attempts.

The Wildcats are just the fifth unranked team to beat an AP top-three opponent after trailing by at least 14 at halftime since 1936, according to Elias Sports Bureau research.

"In the second half we just played very poor football," Oklahoma coach Lincoln Riley said. "We didn't do the things we needed to do to put this game away."

The Sooners led 21-7 at halftime and 35-14 late in the third quarter before the Wildcats mounted a comeback. Riley said his team's early dominance -- the Sooners outgained Kansas State 288 yards to 98 in the first half -- left him hoping for a wider scoring margin at the midpoint.

"The first half was dominant," Riley said. "I remember thinking, 'Man, I don't even know how this game is this close right now.'"

Behind big plays from quarterback Skylar Thompson (334 passing yards, four combined rushing and passing scores), running back Deuce Vaughn (174 combined receiving and rushing yards and a touchdown), a defense that had four takeaways and a special-teams unit that blocked a punt late, the Wildcats were able to turn the tide.

"We bailed ourselves out in that first half when we weren't moving the ball offensively and they were moving it at will," Klieman said. "We had some big interceptions to stop some drives there. And then in the second half, when the game got tighter, our coverage became better, our rush became better."

Asked what he was most disappointed in from the Sooners, Riley said it was "tough to pick, sadly."

"All three sides shared in it," Riley said. While Kansas State had four takeaways, Oklahoma forced no turnovers, a common theme for the Sooners' 2019 defense. Said defensive coordinator Alex Grinch: "It's a results business and we failed."

K-State had 302 offensive yards in the second half and averaged 10.1 yards per play in that span. Klieman was pleased with his team's performance, especially considering how many key players were missing.

On Monday, Klieman mentioned that as the Wildcats had a dozen players return who missed their Sept. 12 season opener vs. Arkansas State, they lost another 10 players to positive COVID-19 test results or contact tracing. He said on Saturday that he wasn't certain the Oklahoma game would be played until Friday. He said he was excited to see several other players get opportunities and succeed in the midst of those absences.

"Knock on wood because who knows who's gonna be available next week, you know?" Klieman said. "And that's kind of what everybody has to realize on our team and across college football. This is a great win ... OK, now we got to go back on Monday and see who's available and get those guys ready to play, whoever that is.

"I hate to say that and you guys don't want to hear that, but that's, unfortunately, the reality we're living in."

Thompson, who also played a significant role in Kansas State's 2019 upset of the Sooners, said he was proud of his team's perseverance.

"We could have easily given up and laid an egg today, but we didn't," Thompson said. "We were down three touchdowns. We had penalties. We made mistakes. But this team just kept grinding and kept believing. It was so special to be a part of, and I'll remember it for the rest of my life."

ESPN's Adam Rittenberg contributed to this report.