Westbrook has not played in the series against his former team due to a strained right quadriceps. He was listed as out in the league's 11 a.m. official injury report but was upgraded early Wednesday afternoon.
Sources told ESPN's Adrian Wojnarowski that a decision would be made about Westbrook's availability after he tests his quadriceps on the court before Game 5.
Westbrook went through an intense pregame workout before the Rockets' Game 4 loss Monday and participated in most of Tuesday's practice. Sources said he felt good when he woke up Wednesday morning and pushed to attempt to play with the series tied, 2-2.
Westbrook, who arrived late to the NBA's Walt Disney World campus due to testing positive for COVID-19, played in only four games during the seeding schedule. His quadriceps injury originally was diagnosed as a contusion, but after Westbrook played 28 minutes in an Aug. 11 loss to the San Antonio Spurs, an MRI revealed the strain.
Westbrook, the 2016-17 MVP who spent the first 11 years of his career with the Thunder, averaged 27.2 points, 7.9 rebounds and 7.0 assists for the Rockets during the regular season.