The Rolex 24 continued with its third consecutive caution-free hour of racing. With only four pace car periods so far, the 56th running of the Daytona classic threatens to break the all-time distance records.

The record for the current 3.56-mile circuit was set in 1992 by Nissan Motorsports, which completed 762 laps for 2,712.72 miles. The all-time mark was set by JLP in the caution-free 1982 race, which covered 2,760.96 miles. The original 3.84-mile circuit featured a longer Pedro Rodriguez Horseshoe in the infield and no chicane on the back straight.

• Hour 21 results

Joao Barbosa continues to lead in the No.5 Mustang Sampling Cadillac DPi-V.R. That car has led since lap 516, when Barbosa took the lead from Acura Team Penske driver Helio Castroneves on a pit stop under caution. Second, three laps down, was the Action Express team car with Felipe Nasr driving the No.31 Whelen Engineering Cadillac.

Ford has run 1-2 in GTLM since lap 202, when both Sebastien Bourdais and Scott Dixon passed the Porsche of Patrick Pilet. The Chip Ganassi Racing Ford team has led all but 10 laps in the class so far today.

Four cars remain on the lead lap in GTD. Franck Perera in the No.11 Lamborghini led Luca Stolz in the No.33 Mercedes by 19.264 seconds. Also on the lead lap were AJ Allmendinger in the No 86 Acura, 22.464 seconds back, and Bryan Sellers in the No.48 Lamborghini, 25.629 seconds in arrears.

RACER.com’s coverage of the Rolex 24 At Daytona is presented by Forgeline Motorsports, manufacturers of custom made-to-order lightweight forged aluminum street and racing performance wheels.