The #17 Porsche 919 Hybrid of Mark Webber, Brendon Hartley and Timo Bernhard won the Austin round of the FIA World Endurance Championship in dramatic fashion as the sister #18 car hit mechanical issues late on.
Romain Dumas was comfortably leading the race with 35 minutes remaining when an electrical glitch forced his Porsche into the garage.
Dumas did recover the ailing #18 car for the final few laps, but could only muster a 12th place finish.
Webber controlled the race in the early stages, taking the lead at turn one with a decisive pass on the inside of his team-mate Neel Jani. The Australian then set about manufacturing a large gap between himself and the other Porsche, with the pairs of Audis and Toyotas locked in their own battles further back.
However, Webber’s work was undone when a one minute stop-go penalty was administered for a pit stop violation. This put the Jani/Lieb/Dumas Porsche back into the ascendancy but the tides soon turned again when Dumas hit trouble.
This allowed the championship leading Audi R18 etron quattro of Andre Lotterer, Benoit Treluyer and Marcel Fassler, which had been running in the shadows of the superior Porsches all evening, to inherit the second podium spot.
Lotterer passed the other Audi, driven by Lucas di Grassi, Loic Duval and Oliver Jarvis, in the final moments but could provide no answer to the one minute advantage held by the winning Porsche.
Toyota completed the top four thanks to a solid run from the #1 TS040 Hybrid of Anthony Davidson, Sebastien Buemi and Kazuki Nakajima, but the sheer pace of the German manufacturers meant that this car would finish two laps off the pace.
The second TS040 Hybrid, driven by Stephane Sarrazin, Mike Conway and Alex Wurz, was one of just two overall retirements after Conway crashed near the halfway mark.
LMP2 honours went to the Silverstone-winning Ligier JS P2 of G-Drive Racing. The Roman Rusinov, Julien Canal and Sam Bird entry took the chequered flag over a minute ahead of the KCMG ORECA 05 – driven by Matt Howson, Richard Bradley and Nicolas Lapierre – after a race long battle between the two.
However, the pace of the Ligier around the 3.4 mile COTA circuit was too much for the KCMG squad, which lost all chances of victory near the end of the race when the car was called for a stop-go penalty.
In third was the #28 G-Drive Ligier of Gustavo Yacaman, Pipo Derani and Ricardo Gonzalez, while Extreme Speed Motorsports finished fourth despite having the early pace to challenge for a podium.
This tightens up the LMP2 order, with the Bird/Rusinov/Canal car now just 14 points behind the KCMG entry. The sister G-Drive machine lies a further four points back.
The GTE-Pro class was won by Porsche for the second race in a row.
Olaf Manthey’s 911 RSRs were convincingly quicker than the other manufacturers, with the car driven by Richard Lietz and Michael Christensen finishing seven seconds ahead of the sister machine of Patrick Pilet and Fred Makowiecki.
Third place went to the AF Corse Ferrari of James Calado and Davide Rigon, who subsequently surrendered their championship lead to the winning Porsche, while the pole-sitting Aston Martin Vantage of Fernando Rees, Alex MacDowall and Richie Stanaway ended the race fourth, a lap down on the Porsches.
Lietz now sits on his own at the top of the standings, with an 11 points advantage over Calado and Rigon heading into the 6 Hours of Fuji.
SMP Racing came from the back of the field to secure a hat-trick of race victories in GTE-Am.
The Ferrari 458 Italia, driven by Victor Shaytar, Andrea Bertolini and Aleksey Basov, resisted the evident pace of the Porsche 911s to claim the win by a margin of 40 seconds.
The Abu Dhabi Proton Racing Porsche finished second, while the AF Corse Ferrari of Emmanuel Collard, Rui Aguas and Francois Perrodo maintained its 100% podium record in 2015 despite incurring an early drive through penalty.
SMP Racing therefore extends its championship lead over the AF Corse entry to 35 points, with the #98 Aston Martin dropping to third in the standings after a disappointing 5th place result.
In terms of the overall FIA WEC championship, the #7 Audi of Lotterer, Treluyer and Fassler remains at the top of the order despite a trio of wins for Porsche. However, the lead to the Webber/Hartley/Bernhard car has been reduced to 10 points as the teams prepare to head to Fuji. The second Porsche is third overall, but lies 35.5 points adrift of the Audi.
The manufacturers’ table is slightly different, with Porsche leading Audi by 218 points to 184. Toyota continues to languish in third, with 101 points.