Looney has been nursing a non-displaced fracture of his right first costal cartilage since Game 2 of the Finals.
The Warriors held Looney out of Game 3 with the injury, but he's been able to play the past two contests. He played 18 minutes Monday night before being removed in the third quarter after reaggravating the injury.
Per Mark Medina of the Bay Area News Group, Looney expects to play in Game 6 because he didn't do any additional damage to his initial injury.
"They said nothing got worse, but it's about me dealing with the pain," Looney said. "I feel confident I should be able to play through it."
Golden State lost Kevin Durant in the first half of Game 5 when he suffered another lower-leg injury that is believed to be an Achilles tear. The two-time defending NBA champions face another must-win Thursday to force a decisive seventh game back in Toronto.
Looney has been instrumental in the Warriors' playoff run thanks mostly to his contributions on defense. He's averaging 5.8 points and 3.3 rebounds in four games against the Raptors.