Denny Hamlin was fastest in opening Coca-Cola 600 practice at Charlotte Motor Speedway with a lap of 190.134 mph.
The lap was the last one Hamlin put down in the session and only his fifth overall. Hamlin topped the board over Ryan Blaney, who ran a 189.673 mph lap.
Completing the top five were Brad Keselowski (189.434 mph), Austin Dillon (189.414 mph) and Erik Jones (189.261 mph). Dillon is the defending race winner.
There were no incidents during the 50-minute session, which is the only practice time slated for Thursday.
The rest of the top 10 were Chase Elliott (189.062 mph), Daniel Suarez (188.910 mph), Martin Truex Jr. (188.877 mph), Kyle Larson (188.838 mph) and Aric Almirola (188.462 mph).
William Byron and Jeffrey Earnhardt, who is in the No. 55 this weekend, ran the most laps in the session at 10.
Ten drivers had to serve 15-minute practice holds for various infractions: Ricky Stenhouse Jr., Matt DiBenedetto, AJ Allmendinger, Kasey Kahne, Austin Dillon, Kevin Harvick, Daniel Suarez, David Ragan, Jimmie Johnson and Ross Chastain.
NEXT UP: Qualifying at 7:15 p.m. ET