Le Mans 24 Hours winners Andre Lotterer, Benoit Treluyer and Marcel Fassler set the pace in first free practice as the FIA World Endurance Championship fired back into action at the Circuit of the Americas following a three month break.

The fourth round of the eight-event season, the 'Lone Star' race opened up with a 90min free practice session with Audi emerging in front of its Porsche and Toyota rivals, the No.2 and No.1 machines separated by just two tenths of a second.

Returning to action following its impressive success at Le Mans, the two Audi R18 entries enjoyed an eight and six tenths advantage over the third place Porsche of Mark Webber, Brendon Hartley and Timo Bernhard, the trio ending up third having led the session for a time.

Related Articles

The championship leading #8 Toyota of Anthony Davidson, Sebastien Buemi and Nicolas Lapierre fronted the Japanese firm's challenge in fourth, ahead of the sister #7 car of Alex Wurz, Stephane Sarrazin and Mike Conway, the latter making his debut with the team this weekend in place of the Super Formula-committed Kazuki Nakajima.

Behind the leading LMP1-H runners, Rebellion Racing headed up the LMP1-L order with the #12 car of Formula E rivals Nicolas Prost and Nick Heidfeld, but the #13 machine managed just three laps en route to 11th. The new Lotus LMP1 entry, meanwhile, notched up 11 laps and was ten seconds off the leading pace.

In the LMP2 class, the wild-card Extreme Speed Motorsports HPD-Honda was quickest from the G-Drive Morgan and KCMG Oreca, while the LM GT classes were headed up by a trio of Aston Martins, the GTE Pro Vantage V8 of Stefan Mucke and Darren Turner leading the factory GTE Am machines