Lewis Hamilton asserted his advantage over championship rival Nico Rosberg in the final session of practice for the US Grand Prix, setting a time 0.884s quicker than his Mercedes team-mate. The pair were split by just 0.003s in Friday practice, but on Saturday morning Rosberg struggled to hook up a good lap after being hampered by slow traffic on his out lap, which cooled his tyres before his final run. Nevertheless, the size of the gap at this stage of the weekend means Hamilton enters qualifying as the favourite to take pole position despite a spin earlier in the session under heavy braking for Turn 12. Once again, the Mercedes pair were in a league of their own with Williams driver Felipe Massa 1.107s adrift in third place and Valtteri Bottas fourth. Fernando Alonso completed a lap on the ragged edge to go fifth fastest, but was more than 1.6s off the pace of the Mercedes pair. His Ferrari swung into a wild slide coming out of the first corner, which cost him time through the rest of the opening sector, and he ran clear off the track at the penultimate corner but still held it together on the exit. Daniel Ricciardo was sixth fastest for Red Bull as team-mate Sebastian Vettel propped up the bottom of the timesheets. The world champion is expected to complete just one lap in qualifying as a complete change of his car's power unit means he will be forced to start from the pit lane in Sunday's race. His running in FP3 was therefore focused on heavy-fuel race runs rather than perfecting a qualifying set-up. Adrian Sutil made a rare appearance in the top ten for Sauber and beat Kimi Raikkonen and Jenson Button to eighth place. Kevin Magnussen was just outside the top ten in the second McLaren as the team looks set for a tricky weekend. The two Toro Rossos were off the pace but could both be facing penalties for engine changes, which will likely leave them at the back of the grid.