O'Neal said Warhol asked him in 1980 whether Fawcett would be interested in being the subject of a portrait and that she agreed. The actor said he requested two versions since he and Fawcett kept separate homes.
He said Warhol made the portrait within two weeks of a brief photo shoot with Fawcett in his New York studio.
"It didn't take long," O'Neal, 72, said. "Doing her hair took longer than taking the pictures."
David Beck, an attorney for the University of Texas, challenged O'Neal, suggesting Warhol approached Fawcett directly about the portrait session during a luncheon in Houston in 1980.
Beck said there was no mention in a journal kept by O'Neal about a deal with Warhol. The actor said some of his journal from that time period had been lost.
O'Neal's testimony was at times testy and emotional, with the actor nearly breaking down when he read a letter Fawcett wrote to the couple's son, Redmond.
After Beck asked O'Neal to read passages from his 2012 memoir Both of Us, the actor tersely offered to sign a copy for the lawyer.
Beck also questioned O'Neal about a 1997 incident in which Fawcett caught O'Neal in bed with another woman. The lawyer has contended that changed the pair's relationship and by the following year, the Warhol portrait that hung over O'Neal's bed was moved to the home of the actress.
O'Neal said he asked Fawcett to take the portrait because it was making his new girlfriend uncomfortable. The portrait remained with Fawcett until her death in June 2009. She had Warhol portrait in her living room and the other at her bedroom door.
After Fawcett's death, O'Neal returned to the condominium and removed the portrait outside her bedroom.
Beck questioned whether the actor ever discussed removing the portrait with anyone, including a trustee charged with carrying out Fawcett's final wishes.
"Of course I did," O'Neal said. "I'm sure I did. It wasn't a secret."
The university sued the Love Story star in 2011 seeking the Warhol artwork that its attorneys have said the school wants to display with its twin in the Blanton museum.
O'Neal has countersued, seeking the return of a tablecloth that Warhol drew hearts on and addressed to him and Fawcett.
He told jurors that if he is allowed to keep the Warhol portrait, he will never sell it. His estate documents call for it to be passed down to Redmond O'Neal, he said.
- AP