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Porsche has completed a clean sweep of all three free practice sessions at the Circuit of the Americas after notching up a 1-2 ahead of qualifying.
The #17 Porsche 919 Hybrid set the quickest time of the one hour session with Brendon Hartley at the wheel with a time of 1m 46.435s, which was also the fastest time of the weekend so far by over eight-tenths.
Neel Jani in the sister Porsche grabbed second spot as the Audis were once again left trailing, with Loic Duval's effort in the Audi a full second off the top Porsche.
WEC leaders Andre Lotterer, Benoit Treluyer and Marcel Fassler were left to pick up fourth – where they've been stuck all weekend – but comfortably ahead of the pair of Toyotas in fifth and sixth respectively.
In LMP2, Signatech Alpine made a late blast to lead the category ahead of qualifying with a 1m 56.178s and pinch top spot from KCMG by less than a tenth of a second, with the Hong Kong team looking for its third consecutive victory of 2015 in Austin.
Team Manthay Porsche once again claimed the glory in the GTE Pro category with Aston Martin holding off the Chevrolet in the GTE Am class.