Phoenix is a critical track on the NASCAR calendar, playing host to the season finale where the final four drivers in the playoffs battle it out for the championship.
NASCAR will utilize a 670-horsepower package at all tracks with the exception of superspeedways and the newly reconfigured Atlanta Motor Speedway.
The 550hp aero package was scrapped after testing at Charlotte Motor Speedway in December.
Kyle Busch, a three-time winner at Phoenix Raceway, went for a spin exiting Turn 4 early in the session. Busch narrowly avoided making contact with the outside wall, but he was ultimately able to drive away unscathed.
Reigning series champion and the most recent winner Phoenix Raceway, Kyle Larson, was on track Tuesday morning as well. Here's a look at the complete list of teams/drivers taking part in this week's test:
Team Penske - Ryan Blaney, Joey Logano
Trackhouse Racing - Daniel Suarez, Ross Chastain
Richard Childress Racing - Tyler Reddick Austin Dillon
Stewart-Haas Racing - Kevin Harvick, Chase Briscoe
Hendrick Motorsports - Kyle Larson, Alex Bowman, William Byron, Chase Elliott
Roush Fenway Keselowski Racing - Chris Buescher, Brad Keselowski
Joe Gibbs Racing - Martin Truex Jr., Kyle Busch
Kaulig Racing - Justin Haley, Daniel Hemric
Wood Brothers Racing - Harrison Burton, Austin Cindric
23XI Racing - Kurt Busch, Bubba Wallace
Front Row Motorsports - Michael McDowell, Todd Gilliland
Petty GMS Racing - Ty Dillon, Erik Jones
JTG Daugherty Racing - Ricky Stenhouse Jr.
Team Hezeberg - Loris Hezemans
