Jenson Button became the first big-name casualty of qualifying at the Circuit of the Americas after his McLaren lost power in the crucial final minutes of the second phase on Saturday afternoon.
The Briton was in the lower reaches of the top ten at the time and, despite clinging on to tenth for a while after limping back to the pits, was eventually displaced by Michael Schumacher and, when it proved impossible to repair the problem, he also fell behind Bruno Senna to wind up twelfth overall. That could improve by one place, giving the Briton a vital odd-numbered grid slot, when Romain Grosjean takes his penalty for changing a gearbox before qualifying, but will still be frustrating to Button, who was challenging for top spot in FP3. Schumacher could also be penalised after appearing to block Fernando Alonso on their early laps.
Joining Senna and Button on the sidelines will be Paul di Resta, Jean-Eric Vergne, Sergio Perez - in front of a large Mexican contingent - Kamui Kobayashi and Nico Rosberg, the German showing that his Q1 struggle was not an isolated incident.
Sebastian Vettel again led the way at the top of the timesheets, underlining the superiority that has seen him pace every session so far. The German usurped Lewis Hamilton from P1 with the first lap in the 1min 35s this weekend and then went on to improve to a 1min 35.796secs effort to maintain the half-second advantage he showed in Q1.
Red Bull team-mate Mark Webber joins Vettel and Hamilton in the pole position shoot-out, along with Nico Hulkenberg, Grosjean, Pastor Maldonado, Felipe Massa, Kimi Raikkonen, Schumacher and Alonso.