Daniel Ricciardo came off worst in a personal battle for Q1 survival with Nico Rosberg after the German just edged his Mercedes out of the drop-zone in the final moments of the session.
While Toro Rosso team-mate Jean-Eric Vergne, a regular Q1 casualty in his rookie year, comfortably avoided the cut in 15th spot, Ricciardo and Rosberg swapped 17th spot several times before the German found a couple of tenths to ensure that he progressed to the second phase of the knock-out session. Ricciardo, meanwhile, will join the usual suspects in the early bath, with Marussia's Timo Glock coming out on top of the third division scrap ahead of team-mate Charles Pic, as Caterham struggled to match the red-and-black cars over the 20-minute session. HRT unsurprisingly brought up the rear, with Narain Karthikeyan bringing out a late yellow flag as he cruised to a halt at turn two, but both the Indian and team-mate Pedro de la Rosa made it inside the 107 per cent mark needed to start the race on Sunday.
While Rosberg could not replicate the performance that saw him take a top ten slot in FP3, the other names at the top of the charts were more familiar, with Sebastian Vettel enjoying a half-second advantage over the field. Lewis Hamilton was second fastest, from Mark Webber, Romain Grosjean - who set the early pave after hearing of his five-place grid penalty - and Bruno Senna.
Most drivers needed several laps to get their tyres into optimum working range, and there was an interesting mix of prime and option tyres on show as they sought grip on the still slippery Circuit of the Americas layout.