Without any help, Osby and the Sooners are all out of the tournament together.
Osby scored 22 points and had eight rebounds in the Sooners' 70-55 loss to San Diego State on Friday night. Jamaal Franklin scored 21 points and James Rahon had 17 for the Aztecs to earn their third NCAA tournament victory.
The seventh-seeded Aztecs (23-10) will play No. 15 seed Florida Gulf Coast on Sunday in the South Regional.
Osby, the first-team All-Big 12 senior guard, was 10th-seeded Oklahoma's lone sense of hope. Every time the Aztecs seemed they might stretch their lead even more, Osby was there with a short jumper or tough basket inside. Osby, though, left the court with a loss in his final game. No other player hit double digits for the Sooners.
"I want to leave a stamp of, hey, this program is back and we're on to bigger and better things," he said. "We just don't want to look back from here."
Behind Osby, Oklahoma led 33-31 at the break. With no other support, the Sooners (20-12) couldn't keep it going another 20 minutes. The Sooners shot 37 percent in the second half and missed 16 of 21 3-point attempts.
"The timing of not making shots was not good," coach Lon Kruger said.
Kruger became the first coach to lead five different programs to the NCAA tournament. He brought Kansas State, Florida, Illinois and UNLV into the tournament.
"They stated as a goal back in November and October that they wanted to play in the tournament," Kruger said. "I don't know that a lot of people really gave them a lot of attention to that. They just kept grinding and improving."
The seventh-seeded Aztecs (23-10) found a way to play another game.
San Diego State traveled 2,732 miles to play in the NCAA tournament. The Aztecs surely didn't mind delaying their return trip home.
Beat the Eagles, and they'll be in the round of 16 for the second time in three years. Coach Steve Fisher was proud Franklin, Rahon, and Chase Tapley had been a part of the program for all of the Aztecs' NCAA victories.
"We are hungry to add to it and proud of the fact that we got one tonight," Fisher said.
The Aztecs outrebounded the Sooners 40-29 and used a modest 8-0 run late in the second half to snap a tie game and take control. The Aztecs are in the tournament for the fourth straight season but they had only won games in 2011 when they reached the round of 16.
Built around upperclassman, the Aztecs firmly believed they had a deep run ahead and wanted to send out seniors like Tapley and DeShawn Stephens (11 rebounds) as winners. They treated the game like a business trip and played like it.
"You just want to go to your teammates and just hug them," Tapley said. "We just accomplished something. Let's keep on going."
Basketball fans looking for YouTube worthy highlights in this game to go with the big upsets and eye-popping plays had to turn to the rest of field. Most of the crowd of 20,125 - perhaps spent from watching the Florida Gulf Coast-Georgetown upset - left by the time the Aztecs wrapped this one up.
There was nothing spectacular about the way the Aztecs constructed their win. They just methodically picked apart OU's defense one open look at a time.
Tapley snapped a 50-all tie with a layup and Stephens made a fantastic out-of-nowhere tip in off a missed layup during a routine 8-0 run that, fittingly, was the difference.
Osby broke up the fun with a 3 to keep the Sooners within striking distance
But Rahon hit a 3 and Franklin buried a long jumper for a 10-point lead. Rahon jogged off the court during a substitution to an appreciative ovation from the fans behind the bench. Coach Steve Fisher slapped him on the back for job well done.
Franklin said nothing has topped the run to the regionals semifinals in 2011. But he'd like to try.
"I have so many memories that I can't say this memory is the best I have," he said. "I'm just thankful to be on the San Diego State basketball team."
Once the Aztecs broke through and took the lead for good, they simply made the parade of free throws in the final minutes to seal it. A small pocket of fans chanted "Coach! Coach! Coach!" as Fisher walked off a winner. The Aztecs made 16 of 17 free throws; OU was just 4 of 8.