Smart tried to block Jaye Crockett's dunk attempt from behind with 6.2 seconds to go but stumbled out of bounds behind the basket. As he was being helped up, he appeared to exchange words with a fan in the front row before lunging for the fan and pushing him with two hands. The fan, wearing a black Texas Tech shirt, stumbled backward but did not fall.
Smart then walked away, pointing back in the fan's direction. Officials assessed a technical foul but did not eject him, and he remained on the bench until the final buzzer.
The fan who Smart shoved is Jeff Orr, an air traffic controller in Waco, Texas, who travels thousands of miles each year to attend Texas Tech basketball games, according to athletic department spokesman Blayne Beal.
Smart has claimed to Oklahoma State coaches that Orr called him a racial slur, a member of the basketball program confirmed to ESPN.
After the game, Smart was "down and remorseful," the team official told ESPN, claiming that the sophomore guard "got caught up in the moment."
The Big 12 has set up a news conference for Sunday afternoon. Following that, Oklahoma State has scheduled a news conference for 6 p.m. ET at which Smart will speak.
Big 12 commissioner Bob Bowlsby will review the incident Sunday under the conference's sportsmanship policy, a conference official told ESPN. Bowlsby has a number of options at his disposal for Smart, from a private reprimand to a public reprimand to a suspension. Oklahoma State will have the ability to provide its side of the story.
"The Big 12 will talk with parties at both Oklahoma State and Texas Tech in the process of reviewing this matter," the official said in a statement.
Big 12 coordinator of officials Curtis Shaw told ESPN that the officials don't have jurisdiction to eject a player who is involved in an altercation with a fan.
"There is no precedent for that," Shaw said. "Our rules are for flagrant 1 or 2. We don't have grounds for dealing with a fan. We don't have a rule to get involved when the player is involved with a fan. We don't know what was said. The official, Doug Sirmons, didn't know what was said."
Shaw said anything involving a fan is up to the host school.
"That's up to the security of the home team and the conference," Shaw said. "We've never had a fan with a player incident before."
Beal told ESPN that high-ranking officials at Texas Tech already have spoken with Orr. Beal said he is uncertain whether the school will issue a statement about the incident.
"We have never had an issue with [Orr] crossing the line in the past," Beal told ESPN.
A video from a Texas Tech game from 2010 appears to show Orr directing an obscene gesture at Texas A&M player Bryan Davis, but Beal said Sunday that the incident did not escalate.
"We are not endorsing that gesture from the Texas A&M game," Beal said. "It just did not rise up to be any kind of issue."
Davis wrote on Twitter that he remembered Orr but disagreed with Smart's actions.