Nico Rosberg claimed pole position for the United States Grand Prix, after worsening rain caused the cancellation of the final segment of a postponed Formula 1 qualifying session.

Qualifying was delayed until Sunday morning at Circuit of The Americas after heavy rain washed out Saturday afternoon’s planned track action, but worsening conditions through Sunday morning meant the session had to be suspended after Q2.

The current forecast calls for the weather to clear in time for the race start at 2 p.m., but the way things have gone these past two days, there are no guarantees…

Rosberg set the fastest time in the second segment, a tenth clear of Mercedes teammate Lewis Hamilton, who Rosberg must beat in the race if he is to prevent Hamilton clinching a third world championship this afternoon.

Daniel Ricciardo’s Red Bull was fastest of all in Q1, but he ended up third on the grid, over a second slower than the two Mercedes. His teammate Daniil Kvyat was fourth fastest, just ahead of Sebastian Vettel, who will receive a 10-place grid penalty for taking a fresh engine this weekend.

Sergio Perez beat Force India teammate Nico Hulkenberg to the sixth fastest time by just over a tenth, while Kimi Raikkonen (who will also take a grid penalty), Felipe Massa and Max Verstappen rounded out the top 10.

Fernando Alonso’s predictions of a possible top-10 position in qualifying almost came true, as the McLaren driver missed out by less than a tenth of a second to Verstappen in Q2.

Several drivers, including reigning world champion Hamilton and 2007 title winner Raikkonen, survived lurid moments at Turn 10 as rain worsened in this segment of qualifying, and Alonso’s teammate Jenson Button suggested over team radio that conditions were bordering on unsafe.

Splashing to 11th place on the grid for Alonso represented McLaren’s best qualifying result of the season so far, while the second Williams of Valtteri Bottas was 0.069s slower than Alonso in 12th, Bottas complaining of broken suspension on his FW37. The second McLaren of Button split the two Lotuses of Romain Grosjean and Pastor Maldonado in completing the top 15.

Carlos Sainz Jr. joined the Saubers and Manor-Marussias in failing to escape Q1, after crashing heavily in the early stages of that session.

Sainz lost the rear of his Toro Rosso over the curb at Turn 3, before crashing hard into the barriers on the outside of Turn 4 and causing the session to be stopped while marshals recovered his broken STR10. The Spaniard will need permission to start the race from the back of the grid after failing to set a time fast enough to make the 107 percent cut-off.

After the session resumed, Vettel’s Ferrari glanced the barriers following a spin at Turn 10, and the four-time world champion tumbled down the time sheet as others gradually improved their times. The Saubers tried in vain to dislodge Vettel’s Ferrari from 15th spot as Q1 came to a close.

Marcus Ericsson was over a second adrift in the end, while team-ate Nasr was a further 0.9s shy, complaining of “zero rear grip” from his C34.

On home soil, Alexander Rossi claimed bragging rights over Manor teammate Will Stevens, with the American 0.35s quicker than the Briton, the latter coming in just under the 107% time.

UNITED STATES GP GRID

*10-place grid penalties for Vettel and Raikkonen