The final hour of the 51st Rolex 24 at Daytona is setting up to be a dogfight. A full-course caution 23 hours in bunched up the leading Daytona Prototypes with Juan Pablo Montoya in the No. 01 TELMEX/Target Chip Ganassi Racing BMW/Riley ahead of AJ Allmendinger in the No. 60 Michael Shank Racing Ford/Riley.The two battled back and forth following an early yellow flag near the end of the hour. At the time of the yellow, the top four cars were within four seconds.GT was just as close. Rene Rast in the No. 52 APR Motorsport Audi R8 GRAND-AM led a group of seven cars on the lead lap. He was 1.161 seconds clear of Anthony Lazzaro in the No. 69 Ferrari F458 from AIM Autosport FXDD. The pole-sitting No. 44 Magnus Racing Porsche GT3 was next in the queue with Richard Lietz at the wheel.There was no change in GX as David Donohue continued to lead for Napleton Racing. The No. 16 Porsche Cayman was nine laps up on Seth Thomas and the No. 22 Bullet Racing Cayman.