Wayne Taylor Racing's Max Angelelli led the Rolex 24 at Daytona through half distance as overnight rain shook up the early status quo.
The three Cadillac DPis had dominated the early part of the race, with the #10 WTR runner battling for the lead with the two Action Express entries throughout the first six hours.
The #31 Action Express car was forced to pit for repairs during the eighth hour following an earlier clash with the #88 Starworks Motorsport Prototype Challenge entry, dropping out of the battle for the lead in the process.
Rain had allowed the #22 Tequila Patron ESM car move into the fight for the lead, only for Brendon Hartley to get caught up with one of the GTD Porsches and fall back down the class field.
At the 12-hour mark, Angelelli led from the #90 Visit Florida Racing Multimatic/Riley Mk30, with the #5 Action Express Cadillac running third, one lap down on the leader.
Prototype Challenge had just three cars still running in its class, with Patricio O'Ward enjoying a six-lap lead over the field in the #38 Performance Tech Motorsports ORECA.
In GTLM, Porsche took control of its class when the rain hit after seeing Ford and Ferrari share the lead early on. Porsche's #912 led at the 12-hour mark from the #911, with the #66 Ford GT sitting third in class ahead of the top Ferrari.
A closely-knit pack in GTD was headed up by the #86 Michael Shank Racing Acura, racing in its debut event, at the halfway mark.