AUSTIN Texas (Reuters) - Lewis Hamilton's U.S. Grand Prix victory means the Briton can now secure his second Formula One title without having to win again but there could still be a sting in the tail.
The specter of double points, a novelty introduced for the first time for the final race in Abu Dhabi, hangs over the championship and is causing some trepidation at Mercedes.
Whatever happens in Brazil next weekend, Sunday's result means the championship cannot now be decided until the race at Yas Marina on Nov. 23.
"I don't have a fear, but I think the last race with the double points has the potential to overshadow the season," said Mercedes motorsport head Toto Wolff after Hamilton chalked up his 10th win of the season and fifth in succession.
Mercedes are sure of both titles now with Hamilton and team mate Nico Rosberg the only drivers still in championship contention with two races remaining, but a controversial finish could take the gloss off the team's achievements.
It would be a travesty if Hamilton did not prevail, with Rosberg only winning four of the 17 races so far, but the two are only 24 points apart.
That means Hamilton could triumph in Brazil next weekend and still ultimately lose out, even if Rosberg draws a blank at Interlagos, if he suffers a retirement in Abu Dhabi and the German wins.
On a more positive note for the Briton, two second places would be ample to secure the title even with double points.
"We know why the double points came, and it made sense in the world to make it spectacular for the audience, the fans and the viewers," said Wolff.
"But now we are in a situation where it could change the outcome."
The rule change, championed by commercial supremo Bernie Ecclestone, was designed primarily to ensure after four years of domination by Red Bull and Sebastian Vettel the title battle went to the wire.
In that it has succeeded, even if there is now the risk of leaving fans -- many of whom dislike what they see as a gimmick -- facing an unprecedented situation and feeling cheated of a deserving winner.
Only two other drivers, multiple champions Michael Schumacher and Sebastian Vettel, have ever won 10 races in a season and never before has the winner of even nine not won the championship.
Under the old format, Hamilton would be on the brink of glory with a race to spare but he said nothing would change in his approach from now to the end.
"I think during the year you have to be balanced in the risks you take and I think that so far I've not been taking too many risks," he said.
"I've done what I've needed to do to get by in the safest way, in the cleanest way, which has worked all year, so I should just continue to do the same."
There are also records to set, with Mercedes equaling on Sunday McLaren's 1988 achievement of 10 one-two finishes in a season.
Wolff said that feat, in a season that has already had people harking back to the great years of Alain Prost's rivalry with Ayrton Senna, made him particularly proud of what Mercedes have achieved.
"As a kid I remember this dominant season of McLaren. I remember seeing those cars scoring one-twos all the time up to a point that it was almost boring. It was just pure dominance," he told reporters.
"For us to equal that record, and to be able to do one or two more, is proof the team has done many things right and we have taken many good decisions.
"Normally I don't care about statistics, but that one is something which reminds me of many years ago."
Editing by Greg Stutchbury