OSU's hopes of finishing among the Big 12's top four teams in the regular season standings - which would result in a first-round bye in next week's postseason tournament - also took a major blow with the loss. The Cowboys are now 7-8 in Big 12 play.
Oklahoma, which has now beat Oklahoma State six of the last eight times they've played (including a sweep of the two-game series this season), was playing without standout freshman Blake Griffin. The 6-foot-10 Griffin leads the Sooners in scoring (15.2 points) and rebounding (9.3) but didn't even make the trip to Stillwater after having arthroscopic knee surgery Sunday.
"I was concerned about this. I knew something like this was capable of happening," OSU head coach Sean Sutton said. "I spent the last two days talking to our guys about not letting down their guard just because Blake wasn't playing in this game. I have seen over the years situations like this before where a team's best player is out and all of a sudden other guys on the team elevate their games and come in and play at a high level.
"I thought it was going to be a dogfight the last two days. I thought they played awful well, and played disciplined and did the things they needed to do to win a game like this. At the other end, I don't think our guys played with the discipline they've been playing with and made some mental mistakes.
"We had to do a good job on their guards, and pressure them and not give them open three-point shots," Sutton continued. "I thought their guards played better than ours, and that was one of the big keys. Our defensive intensity wasn't anything like we've seen the last two or three weeks."
The loss spoiled the final regular season home game at Gallagher-Iba Arena for two OSU seniors – Marcus Dove and Tyler Hatch. Dove finished with 13 points and 10 rebounds – the second double-double of his career – but it wasn't enough as the crowd of 13,910 (the largest of the season) went home disappointed.
"I'm very disappointed," said Dove. "We just got out-toughed and out-played, and I am embarrassed."
Cowboy point guard Byron Eaton said, "I'm disappointed for Marcus and Tyler. On my way out, I want to go out with a win, and I know these guys wanted to go out with a win as well. Not only that, but this could have been a big step closer to the NCAA Tournament. Now we are one step back. I'm sorry for not helping my friends go out the way they wanted to, but now all I can do is elevate my game a little bit more so I can get these guys to the NCAA Tournament."
The Cowboys finish the regular season in a nationally televised game (ESPN) Sunday afternoon against ninth-ranked Texas (25-5 overall and 12-3 in the Big 12) in Austin. OSU lost to Texas 63-61 at Gallagher-Iba Arena on Jan. 21.
"We can't shut it down. We've got to fight back. We got ourselves out of one hole," Sutton said. "This is a disappointing loss to say the least, but we've got to come back and compete and fight Sunday, and go to Texas and see if we can play well and win that game and get our confidence going again. I just don't know what was going on tonight. I really don't. It didn't even look like the same team out there, but I think they'll bounce back.
"I think we can (win at Texas), but we're going to have to play better than we did tonight," Sutton continued. "We're going to have to remember what got us in this position, and that's playing tough, aggressive sound defense, making smart decisions on the offensive end, showing patience and taking good shots, sharing the basketball, all the things that helped us win five games in a row. A lot of that was just out the window tonight. We didn't do any of those things. That's what's just maddening to me.
"It wasn't like it was the same team that I've been watching. I don't know why that was, especially in a game like this that meant so much."
The Cowboys were led by Obi Muonelo with 15 points, while Byron Eaton and Marcus Dove each scored 13.
"It's a tough loss. I feel for our fans, I feel for Marcus and Tyler, but Oklahoma played a heckuva basketball game," Sutton said.