Updated

By Deborah Charles

VANCOUVER (Reuters) - Seth Wescott made a huge comeback on the final jump to defend his Olympic snowboard cross gold on Monday, leaving another Canadian to settle for second best against an ice-cool American rival.

Wescott, who won the sport's debut gold in Turin, started the race in the back of the four-man pack but then began to make his move after team mate Nate Holland spun out about halfway through.

Cheered on by the partisan Cypress Mountain crowd, Robertson had led for most of the race where four athletes face off in snowboard's version of motocross along a long course full of steep turns and jumps.

But then Wescott passed France's Tony Ramoin then pulled even with Robertson as they neared the final turn and jump of the long, technically challenging course.

As is often the case in the anything-can-happen sport of snowboard cross, the Canadian lost ground when he made a slight mistake and when the American took a tighter line in the final turn.

The crowd, which had been chanting Robertson's name and seeming sure of his victory, seemed stunned into silence at the very end when Wescott pulled it out in the end.

"I think I felt them collectively get bummed out when I made the pass," Wescott said.

Robertson said he felt in control throughout the race, until he came up short on the last jump.

"As soon as I came up short on that jump I knew someone was going to pass me. But whatever, this happens," said Robertson, whose close miss for gold mirrored his freestyle skiing teammate Jenn Heil who was pipped by American Hannah Kearney for gold in the moguls on Saturday.

Ramoin took the bronze behind Robertson.

Several of the medal favorites, including France's Pierre Vaultier and American Graham Watanabe, crashed out before the semi-finals.

(additional reporting by Nicole Mordant)

(Editing by Miles Evans)