Both Kyle Larson and Michael Waltrip will drive their backup cars in Thursday night's Daytona 500 qualifying Duel races after a multi-car practice accident on Wednesday.
Ty Dillon instigated the accident during Wednesday night's second practice when his Chevrolet began leaking oil through Turn 2, causing Kurt Busch, Reed Sorensen and Ryan Newman to slow down.
Waltrip, tucked up behind the train of cars, proceeded to collide with the rear of Newman's Richard Childress Racing Chevrolet, forcing the pair into a spin.
Larson and David Gilliland were also involved, with Larson hit from behind by 2015 Xfinity champion Chris Buescher.
Both Larson and Waltrip will be forced to switch to their backup cars, and the pair will start their respective Duel races from the back of the field.
NASCAR extended practice by five minutes to account for the stoppage, with rookie Brian Scott ending the session fastest for Richard Petty Motorsports, ahead of Austin Dillon and reigning Sprint Cup champion Kyle Busch.
Two-time Daytona 500 winner Jimmie Johnson was fourth from Paul Menard.
Michael McDowell topped the earlier practice session, with 500 poleman Chase Elliott eighth on the leaderboard.