Corvette delighted with qualifying

The two factory C6.Rs qualified nearly three seconds faster than their main rivals, the factory Aston Martins, which were also behind the sole Saleen and Lamborghini entries.

Johnny O'Connell, who shares the No.63 car with Jan Magnussen and Ron Fellows, was delighted to see both cars setting the pace in the class.

"We're really pleased," he told autosport.com. "We made a lot of changes to our programme based on what we've learned over the past few years. We've made a lot of moves to improve our straight-line speed without sacrificing our cornering, and it's working.

"A lot of people were laughing because in the states we're largely just racing against ourselves, but here I think we've shown that, despite there being nobody to beat in the US, we're still pushing ourselves very hard.

"I don't know whether they're [Aston Martin] holding back a little bit. Our success - we've won five of the last seven - has come as a result of pushing them so hard that they break. This year maybe they need to push us."