Creighton coach Greg McDermott joked that the ruling only added to an already sleepless night ahead of facing the 18th-ranked Sooners.
After battling nerves in a quiet debut, Thomas hopes to show Oklahoma what he can do Wednesday night when its tries to snap the Bluejays' 20-game home winning streak.
Thomas appealed to the NCAA instead of sitting out a year after transferring from Houston. The 6-foot-8 forward averaged 16.2 points and 8.9 rebounds for the Cougars while starting 66 games over the past two seasons.
He was one of only seven to amass 1,300 points and 800 rebounds at the school.
Thomas said he started screaming Saturday night when he finally learned he'd be able to play following a six-month wait. He finished with four points and three rebounds in 23 minutes in Sunday's 78-53 opening home win over Southeastern Louisiana.
"I didn't play as well as I wanted to, but to get that first game out of the way is relieving," Thomas said. "I have had a lot of stress the past couple months, so getting that first game out of the way helps a lot."
McDermott wasn't as jubilant upon hearing the news about Thomas, whose presence should make it more difficult for the Bluejays in their first big test of the season.
"I was watching film and couldn't sleep so that just added to my restlessness, I guess," he said. "If you have a chance to play them, you want to try and beat them at full strength. It'll be a fun night for basketball in Omaha."
Creighton cruised to its second straight win Sunday, 84-66 at home over Chicago State. Center Will Artino has led the way with a combined 34 points and 18 rebounds in two games, while reserve guard Isaiah Zierden has scored 34 and hit 7 of 14 from 3-point range.
The Bluejays have outrebounded their opponents 81-59 heading into a tough matchup with Thomas and Ryan Spangler, who finished with a team-high 11 boards Sunday after averaging a Big 12-best 9.3 last season.
"We're going to see two very good rebounders in (Thomas) and Spangler," McDermott said. "They've have guys in the backcourt that can score, are solid with the basketball and are going to defend."
Oklahoma's Isaiah Cousins added 14 points and 10 rebounds in the opener. Fellow guard Buddy Hield finished with 25 points while setting a school record for 3-point shooting percentage by hitting all seven of his attempts.
"It was great to see Buddy get it in rhythm and the guys do a good job of getting him the ball in rhythm," Oklahoma coach Lon Kruger said.
The Sooners have dropped five of eight nonconference road games, while the Bluejays have won by an average of 18.4 points during a home winning streak that's tied for the seventh longest nationally.
Creighton is also seeking its 47th straight win in regular-season home games before Nov. 26 and seventh in its past 10 at home versus ranked opponents.
Oklahoma has won two of the three all-time matchups.