AUSTIN -- Lewis Hamilton set the fastest time in final practice at the U.S. Grand Prix, completing a clean sweep of all three practice sessions at the Circuit of the Americas ahead of qualifying.
Saturday morning's practice was far more competitive than Friday's with Hamilton's championship rival Sebastian Vettel just 0.092s off the lead Mercedes. The small gap sets up a tantalising battle ahead of qualifying, with the two title rivals in contention for pole position while their teammates Valtteri Bottas and Kimi Raikkonen two tenths adrift in third and fourth.
Vettel's slim championship chances rest on him being able to beat Hamilton this weekend, but on his current form the Mercedes driver remains the clear favourite ahead of qualifying.
The threat from Red Bull took a hit ahead of the session as the team from Milton Keynes was forced to switch the engine and MGU-H on Max Verstappen's car, resulting in a 15-place penalty. Verstappen still finished fifth, but teammate Daniel Ricciardo -- who does not have a penalty this weekend -- was down in ninth.
Felipe Massa managed to haul his Williams up to sixth place with a time 0.868s off Hamilton. After the team's recent struggles, the U.S. Grand Prix could represent a golden opportunity to score a big haul of points, with Massa ahead of both Renaults and the Force Indias.
The battle between new Renault teammates Nico Hulkenberg and Carlos Sainz remained remarkably tight as Hulkenberg just edged Sainz by 0.042s. Unfortunately the battle is unlikely to continue on to race day as Hulkenberg has a 20-place grid penalty for an engine change earlier in the weekend. The Force Indias were also closely matched with Sergio Perez and Esteban Ocon split by 0.163s ahead of the second Williams of Lance Stroll.
After finishing Friday practice seventh fastest, Fernando Alonso and McLaren slipped to 13th on Saturday morning, with Stoffel Vandoorne a further 0.360s off his teammate in 14th.
Brendon Hartley's F1 debut continued in fine form with the 15th fastest time ahead of the highest-placed Haas of Kevin Magnussen. The Saubers of Marcus Ericsson and Pascal Wehrlein were 17th and 18th ahead of Romain Grosjean, who spun off at Turn 7 halfway through the session and beached his Haas in the gravel.
Daniil Kvyat completed just six laps in the Toro Rosso and finished the session last due to a front suspension issue.