Nico Rosberg beat Lewis Hamilton to pole position at the United States Grand Prix to revive his title hopes.
The German, who is 17 points behind his Mercedes team-mate in the world championship, was an impressive 0.376 seconds clear of the British driver.
The Mercedes were well clear in Austin, with Williams's Valtteri Bottas 0.839secs behind Rosberg in third.
His team-mate Felipe Massa was fourth, ahead of Red Bull's Daniel Ricciardo and Ferrari's Fernando Alonso.
Rosberg said going into this weekend that he knew he needed "strong races" in the remaining three events (including Austin, which begins at 20:00 GMT on Sunday) to try and regain the lead from Hamilton, who has won the last four grands prix.
And his performance came despite a troubled time in final practice, in which he was more than 0.8secs slower than Hamilton.
Rosberg said: "Great day. Very happy. It worked out really well. I arrived with a car I was really happy with. The balance was good.
"It was quite a challenge because the wind was changing and this morning the track was a lot colder. The track kept changing so it wasn't easy to get a balance. But the race is what counts."
Hamilton praised Rosberg for a "great job".
"I really struggled with braking," he added. "The left front brake was always around 100C less than the right front brake and it just kept catching, even if I braked earlier. Even if I didn't have that I think Nico was perhaps too quick today."
|2014 title permutations|
|Hamilton has a 17-point lead over Rosberg with 100 points remaining - 25 in the US, 25 in Brazil and 50 in Abu Dhabi.|
|The 2014 Formula 1 world title cannot be won at this weekend's United States Grand Prix.|
|If Lewis Hamilton wins in Austin and Nico Rosberg fails to finish, he will have a 42-point lead going to Brazil. Hamilton would then need to score only eight more points than Rosberg in Brazil to clinch the title.|
|If Rosberg wins in Austin and Hamilton retires, Rosberg will lead the championship by eight points going to Brazil. The title cannot then be won in Brazil, forcing a title decider in Abu Dhabi.|
|If Hamilton wins in Austin and Brazil, with Rosberg second in both, Hamilton will arrive in Abu Dhabi with a 31-point lead. But if Rosberg then wins and Hamilton finishes sixth or lower, Rosberg will win the title.|
McLaren's Jenson Button was seventh, one place ahead of team-mate Kevin Magnussen, but the 2009 world champion will drop five places as a result of a penalty for changing a gearbox before it had done the requisite five races.
Ferrari's Kimi Raikkonen took ninth, ahead of Adrian Sutil's Sauber, the first time the team had made it into the top 10 in qualifying all year.
It gives Sauber a great chance to score their first points of the season - so far, either Sutil or team-mate Esteban Gutierrez have spun out every time they have been close to scoring.
World champion Sebastian Vettel will start from the pit lane after fitting a sixth engine this season - teams are restricted to five.
And Toro Rosso's Daniil Kyat will start last despite qualifying 14th because he has a 10-place penalty for changing his engine and taking his seventh of the season.
Events on track are taking place against the backdrop of a row over F1 finances in the wake of the collapse of the Marussia and Caterham teams in the last two weeks.
The Force India, Lotus and Sauber teams, who are not involved in the rule-making strategy group, are unhappy about their lack of voice and what they see as an inequitable split in F1's income.