Michael Schumacher and Nico Rosberg experienced differing fortunes in qualifying
Seven-times champion fifth; Rosberg 17th in older car
By Mike Wise in Austin
Last Updated: 18/11/12 10:47am
Schumacher exceeded his expectations after setting the sixth fastest time, moving up a place as a result of Romain Grosjean's gearbox penalty.
However, Rosberg fell well below his own after qualifying down in 17th - the team having decided to roll back his W03 chassis to a version featuring an older exhaust system.
Rosberg made the same switch on Friday before changing back to the newer Coanda effect exhaust - which was first raced in Singapore - in Saturday morning's practice session.
But the team decided to go back again in qualifying, a move Rosberg said was made with next season's car in mind.
"Pace-wise was very good this weekend, but we tried our car from four months ago practically. So (we were) going back four months in development," he said.
"On Friday we tried it, but with different (prime) tyres and not for one lap. And on different tyres, on the long run, it looked good - not too far off Michael's car.
"This morning, I was in the current car and we decided 'let's give it a go'. For qualifying, we changed to the older version because it shouldn't be too different and maybe there's something we can learn, especially for the race."
Schumacher's performance was his best since the Italian Grand Prix, where he lined up fourth on the grid.
"We were anticipating just to get into the top 10. That was what we were thinking could be good, maybe seventh or eighth as a max," he said.
"To be sixth and then fifth for that reason is welcome, particularly being on the right side of the grid," added the seven-times World Champion, in reference to the drop-off in grip between the left and right-hand sides.
Schumacher escaped punishment in Q2 after it was decided that he had not impeded Fernando Alonso in the fast sequence of bends between Turns 3 and 6 at the Circuit of The Americas.
The stewards found in Schumacher's favour because both drivers were starting multi-lap stints to get their tyres up to temperature, with Alonso therefore not trying to set a representative time.
Explaining how difficult it is to get Pirelli's hard and medium rubber to perform on the new track surface this weekend, Schumacher said: "The tyres are very crucial, we know this all year long. They're here maybe a little bit more peaky in their behaviour because of the track condition and the circumstances.
Schumacher ran five laps in Q3 before setting a time. Of that session, he added: "I tried already the lap before that and it wasn't yet ready. But then the lap, just everything was switched on and was there."
Rosberg, meanwhile, was left to search for positives.
"We're much further back than expected. It's very, very surprising to lose that much performance. Especially with these tyres: you go a bit slower, you have a bit less grip and it just tips you over the edge. You're nowhere," he added.
"The positive is that we learned something and also you look at the difference between what I did and what Michael did and that proves we're doing well in development and we are moving forward.
"One of the reasons we did it is that we hope that the race will be better. Maybe tomorrow in the race I can be very strong. We'll have to see."