Busch posted the fastest average speed of 130.813 mph early in the 50-minute session Friday at Phoenix Raceway but ran eventually ran into an issue.
Just over 32 minutes into the session, A.J. Allmendinger drifted up the track and into Busch in Turn 4 and the two made contact. Allmendinger spun around which brought out a caution.
The damage did not appear extensive to either car. The session resumed several minutes later.
With less than five minutes remaining, Championship 4 driver Kyle Larson appeared to come close to tagging the Turn 1 wall but escaped any damage to his No. 5 Hendrick Motorsports Chevrolet.
Bubba Wallace ended second-quick (130.676 mph) and title contender Ryan Blaney was third (130.425 mph).
Fellow title contender Christopher Bell was fourth and Ross Chastain rounded out the top five.
Completing the top-10 were Joey Logano, Championship 4 driver William Byron, Tyler Reddick, Ty Gibbs and Brad Keselowski.
Larson was the slowest of the Championship 4 drivers, ending up 11th fastest.
Among those drivers who ran at least 10 consecutive laps, Bell had the fastest average lap speed (129.600 mph). He was followed by Blaney, Byron, Kevin Harvick and Busch in that category.