Lewis Hamilton found himself off the pace in second practice ahead of the United States Grand Prix in Austin on Friday.
Having topped the timesheets in the opening session, the Mercedes driver was third behind team-mate Nico Rosberg and Red Bull's Daniel Ricciardo in FP2.
Hamilton faces an uphill struggle to claw back the 33-point deficit to championship leader Rosberg and needs the German to slip up if he is to retain his crown.
But it was Rosberg who ended the day quickest, posting a lap of one minute, 37.358 seconds on the supersoft tyres - 0.291 seconds quicker than Hamilton.
Ricciardo split the Mercedes by going 0.194 seconds slower than Rosberg.
Sebastian Vettel, who had to finish a lap one-handed in FP1 after heavy contact with a kerb left him clinging onto a wing mirror, went fourth fastest in FP2, with Max Verstappen in fifth.
Force India are looking to stretch their 10-point advantage over Williams in the race for fourth in the constructors' championship and put on a strong showing in free practice.
Nico Hulkenberg and Sergio Perez went sixth and seventh fastest respectively, while Williams duo Valtteri Bottas and Felipe Massa finished 14th and 16th.
McLaren duo Jenson Button and Fernando Alonso ended FP2 ahead of 10th-placed Kimi Raikkonen to round off the top 10.