Ricky Taylor moved in the lead in the #10 Acura ARX-05 minutes after the latest round of pitstops, leapfrogging the similar machine of Meyer Shank driver Helio Castroneves, who took over the driving duties from Tom Blomqvist.
Blomqvist had propelled the #60 Acura ARX-05 to the front of the field after the 14th caution to the race, barging past the #31 Action Express Racing of Tristan Nunez at the restart - having already jumped Tristan Vautier in the #5 JDC-Miller Cadillac for second in the pits.
Nunez was then forced wide off the track by Vautier at the International Horseshoe, dropping to fifth and last among the DPi runners on the lead lap. Vautier was adjudged to be responsible for the incident, earning the JDC-Miller racer a drive-through penalty that he served immediately afterwards.
The incident between AXR’s full-season entry and the similar JDC-Miller machine promoted Earl Bamber’s #02 Chip Ganassi DPi.-V.R to second, having taken over the driving duties from the team’s new signing Alex Lynn.
However, there was more drama for Ganassi as Bamber was soon forced to bring his car to the garage with a broken fuel pump, dropping it to sixth in the class - only ahead of the sister #01 car that had already dropped out of contention with electrical issues.
With three Cadillacs no longer in the fight for victory, Acuras held positions one and two with MSR Acura appearing to have a comfortable lead with just over six hours of racing to run. But after the pitstops shook out Castroneves dropped behind Taylor, who had been sitting a strong second behind MSR’s Blomqvist in the previous stint.
Mike Conway is running third in the best of the Cadillacs, the #31 AXR, with Vautier the last of the DPi cars still in contention for overall victory in fourth.
In the LMP2 class, Ferdinand Habsburg moved into the lead in the #8 Tower Motorsport ORECA 07 after the last round of pitstops, ahead of Rinus Veekay in the #29 Racing Team Nederland.
The #81 DragonSpeed car enjoyed a long stint at the front with Colton Herta at the wheel, but slipped to third after Devlin DeFrancesco took over the driving duties.
The #52 PR1 Mathiasen car was also in the fight for the lead but spun with Scott Huffaker at the wheel, with James Allen stalling his #69 G-Drive car in avoidance.
Allen was unable to get the car going, bringing out the safety car.
In LMP3, the #74 Ligier of Riley Motorsports remains dominant with Michael Cooper at the wheel.
Vanthoor puts KCMG Porsche in GTD Pro lead
The #2 KCMG Porsche 911 GT3-R holds the lead in the GTD Pro following a charging stint from works driver Laurens Vanthoor after the 14th caution of the race.
Having sat fifth in class at the restart, Vanthoor made quick work of the #15 Proton Mercedes AMG GT-3 of Austin Cindric and erstwhile leader Felipe Nasr in the #9 Pfaff Porsche to jump to third place.
The Belgian racer then dispatched the #62 Risi Competizione Ferrari of Davide Rigon, before passing Daniel Juncadella in the #97 WeatherTech Mercedes for the lead of the race.
Nasr now sits second in the #9 Porsche, with Cindric passing Jack Hawksworth in the #14 Vasser Sullivan Lexus for third.
The #97 WeatherTech Mercedes that briefly led in the hands of factory driver Juncadella in the 17th hour remains in the pits with white smoke coming out of the bonnet.
The GTD category is led by Toni Vilander in the #21 AF Corse Ferrari 488, with Richard Lietz second in the #16 Porsche and Jordan Pepper third in the #70 Inception McLaren 720S GT3.