Greg Biffle ended Friday's track time on top of the timesheets after two 115-minute practice sessions at Darlington Raceway in preparation for Sunday evening's Bojangles' Southern 500 NASCAR Sprint Cup Series race.
The Roush Fenway Racing driver, who is a two-time winner at Darlington, set the best lap of the day during the first practice of the day which got underway on the 1.366-mile oval at 11am. The lap clocked in at 27.909s (176.201mph) to pip a trio of Stewart-Haas Racing drivers by 0.057s, led by Kurt Busch followed by his team mates Tony Stewart and Kevin Harvick, the defending race winner at Darlington. Joe Gibbs Racing's Carl Edwards rounded out the top five.
Biffle also maintained the pace in the subsequent early evening session where he was second fastest with a time of 27.960s (175.880mph) in conditions closer to those that the drivers will face for the race itself. Penske's Brad Keselowski left it late, going 0.024s faster than Biffle ten minutes from the end of second practice to claim the session honours in the evening, while Kurt Busch also maintained his earlier pace and was third fastest ahead of Richard Childress Racing team mates Paul Menard and Austin Dillon.
Dillon got a trademark "Darlington stripe" early in first practice after hitting the turn 2 wall, which did extensive damage to the right hand side of the #3 which the team was able to fix rather than breaking out the backup car. Brett Moffitt also got a stripe early in the same session, while Chase Elliott brushed the wall about a half hour into practice. Trevor Bayne also made contact with the wall during midday practice.
However the biggest impacts of the day came in the later practice. First there was Kyle Busch who went into the wall midway through the session and who was forced to unload the backup car for the rest of the weekend. Because the change happened before qualifying, it will not affect his grid position so Busch will not have to start from the back of the grid on Sunday.
Later in the session Harvick followed Busch's lead and also smacked the wall in turn 2.
The drivers had all got extended practice sessions on Friday to allow them to adjust to the new low downforce package which will be used by all cars this weekend. It's the second race of the year to use this new specification, which made its début at Kentucky in July.
Qualifying for the Bojangles' Southern 500 will take place on Saturday afternoon at 1.45pm local time (6.45pm BST). The NASCAR Xfinity Series will also be in action at Darlington on Saturday with the VFW Sport Clips Help a Hero 200, while this weekend's Cup race gets the green flag on Sunday at 7pm (midnight BST).
See full Friday NASCAR Sprint Cup Series practice results from Darlington Raceway.