Porsche has shown strong pace throughout the week at Petit Le Mans but their day went from hero to zero this afternoon at Road Atlanta with all three 911 machines forced to start from the back of the grid tomorrow.

Falken Racing’s Bryan Sellers was the first to strike trouble. The reigning Petit Le Mans race winner ran off the circuit on his first flying lap, crashing in the esses – his first crash for the Derrick Walker-run team since its debuted in 2009.

The pace by the factory cars in qualifying was strong with Earl Bamber setting the fastest time and Nick Tandy following up with a P2 performance.

Bamber became only the second man in the short history of the TUDOR United SportsCar Championship to score more than one GTLM pole – the other being his Le Mans-winning teammate, Tandy.

However, Bamber’s late session crash which eliminated his fastest time appears to have been worse than first thought. While the Kiwi’s second fastest lap was still good enough for pole, the team will be forced to revert to a back-up chassis for the No.912 which will be co-driven by Joerg Bergmeister and Frederic Makowiecki.

Tandy’s No.911 car struck trouble in post-race tech where it suffered a ride height infraction.

Now all three Porsche GTLM machines will have to start from the rear of the grid.

Corvette Racing’s Oliver Gavin will now lead the GTLM pack ahead of BMW’s Lucas Luhr.

The morning warm-up – which now looms as a key shakedown session for the No.17 and No.912 Porsches – kicks off at 9:00am. The final round of the 2015 TUDOR United SportsCar Championship – Petit Le Mans – will go green at 11:10am.