Roush Fenway Racing's Greg Biffle led Friday's first of two practice sessions at Talladega Raceway in advance of Sunday's Hellman's 500.
Biffle's No. 16 Ford had a best lap of 198.949 miles per hour around the mammoth Alabama superspeedway, tops in the field.
Second-fastest was AJ Allmendinger's JTG Racing Chevrolet, followed by Chris Buescher, and Biffle's teammates, Ricky Stenhouse Jr. and Trevor Bayne.
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Practice speeds at Talladega and Daytona, the two restrictor-plate tracks on the NASCAR circuit, are far less predictive of race performance than at shorter tracks. That's because the aerodynamic draft can profoundly affect a car's speed depending on whether the car is running solo (slower) or in a drafting pack (faster).
There are two practice sessions today at Talladega, with the final Happy Hour session scheduled for 4:30 p.m. ET. Qualifying will take place Saturday at 4 p.m. ET.
The Hellman's 500 is the third and final race in the Chase Round of 12. When the checkered flag falls on Sunday, the Chase field will be cut from 12 to eight drivers.
The drivers currently outside the Chase cutoff are Austin Dillon, Denny Hamlin, Brad Keselowski and Chase Elliott.
Check out Friday's complete Practice 1 results below.