Lewis Hamilton celebrates winning the race and the world championship in Austin, Texas October 25, 2015. [Photo/Agencies]

AUSTIN, Texas - Lewis Hamilton joined the elite group of triple Formula One world champions on Sunday after winning a thrilling US Grand Prix that kept the crowd on tenterhooks right to the very end.

"That's the greatest moment of my life," he gasped over the team radio, choking back the tears, after crossing the line 2.8 seconds ahead of German team mate Nico Rosberg who had led before a late mistake.

The first British driver to win back-to-back titles, Hamilton realized a lifelong ambition to equal the tally of his boyhood idol Ayrton Senna, the Brazilian triple champion who died in 1994.

Ferrari's four-times champion Sebastian Vettel finished third, after starting 13th and fighting back to chase Rosberg nose-to-tail over the final lap with the crowd on the edge of their seats on a cold and blustery afternoon after morning rain.

Had Vettel passed Rosberg, the celebrations for the 'double double' -- with Mercedes retaining their constructors' title two weeks ago in Russia -- would have remained on hold.

"I'm just overwhelmed," said Hamilton, who had needed to beat Vettel by nine points and Rosberg by two to take the crown with three races to spare.

"There were so many times when I thought I had lost the race."

Interviewed on the podium by pop's very own 'rocket man', British pop singer Elton John, Hamilton sprayed the champagne with abandon while Rosberg looked shellshocked and barely reacted.