AUSTIN (AFP) - Defending champion Lewis Hamilton kept alive his bid for a fourth world title on Sunday (Oct 23) when he claimed his first victory in six races and the 50th of his Formula One career by winning the United States Grand Prix.

The three-time champion produced a flawless drive from his 58th pole position to finish ahead of his Mercedes team-mate and championship leader Nico Rosberg.

It was Hamilton's fourth win at the Circuit of the Americas in Texas and his fifth United States Grand Prix win, equalling the record set by seven-time champion German Michael Schumacher.

Australian Daniel Ricciardo finished third for Red Bull.

Hamilton's win trimmed Rosberg's lead from 33 points to 26 with three races remaining, but he knows that even if he wins them all Rosberg can take his crown by finishing second in each one.

"This has always been a good hunting ground for me. I love being in the USA. I'm proud of the team's effort this weekend," said the Briton.

Four-time champion Sebastian Vettel came home fourth for Ferrari after team-mate Kimi Raikkonen had been forced into a bizarre retirement when he left the pits with a loose rear wheel.

Ricciardo's feisty Red Bull team-mate Dutch teenager Max Verstappen also retired after a mechanical failure, leaving the way open for two-time champion Fernando Alonso to seize fifth for McLaren-Honda after a late attack on compatriot Carlos Sainz.

Sainz came home sixth for Toro Rosso ahead of Felipe Massa of Williams,Sergio Perez of Force India, Jenson Button in the second McLaren and Romain Grosjean who marked his 100th race by scoring a point for the popular American Haas team on their home soil.