AUSTIN, Texas (AP) When Formula One was last in the United States, Sebastian Vettel had already earned his fourth consecutive world championship in a season of domination not seen since Michael Schumacher's days at Ferrari.
Then came the engine change, from the screeching V8s to the sublime hybrid turbo V6.
The effect was a demolition of an F1 dynasty built by Vettel's Red Bull team in a move that most thought would produce a wide-open title chase in 2014.
Instead, F1 simply exchanged one dominant team for another. Mercedes has crushed the competition with teammates Lewis Hamilton leading Nico Rosberg by just 17 points in the title chase heading into this week's U.S. Grand Prix.
Red Bull's Daniel Ricciardo sits a distant third in the driver's championship with only three races left. Mercedes has already won the constructor's title.
''Success in Formula One does not come easily and we are determined to ensure that our performance this year is not a one-off but the first of many,'' said Toto Wolff, head of Mercedes-Benz Motorsport.
Vettel's 2013 was a performance for the ages. The baby-faced German tied Schumacher's record of 13 victories in 2004, including the last nine of the year. And when he spun circles on the track after his win in Austin, his message to his team was to savor the moment. Even he seemed to know it would all soon end.
Mercedes happily filled the void.
Rosberg won the season-opener in Australia before Hamilton ripped off four wins in a row. Rosberg regained the lead in the title chase until Hamilton surged ahead again by winning the last four races heading into this weekend. Tension between the teammates and old friends has been simmering for months and another Hamilton victory could further put the squeeze on Rosberg.
''It's still all to play for in the battle for the drivers' championship and I won't be giving up the fight,'' Rosberg said.
Hamilton has a previous victory at the Circuit of the Americas in 2012, when he passed Vettel late to steal the win, forcing Vettel to wait until the final race that season to win the championship.
Every point Hamilton can put between himself and Rosberg this week would be precious. Rules changes in place for this season will award double points for the final race in Abu Dhabi on Nov. 23.
The reliability of his car is as big of a concern for Hamilton as Rosberg's driving. Car problems have forced Hamilton to retire early three times this season, twice for Rosberg.
''But the guys have worked very hard to eradicate those through the year, so I hope that we can all go through these next races together as a team, without any of those issues,'' Hamilton said.
Hamilton said he didn't want to even consider a crash or reliability problem that could cost him the title.
''I'm not even going to put that negative energy out there,'' Hamilton said.
Vettel would like to find even a spark of good energy this weekend. It's been a long time since he had any.
His troubles started with a disastrous round of preseason testing that raised alarms about Red Bull's grasp on the new engine technology. An early run of bad form behind Mercedes' dominance quickly killed any hopes of contending for another title.
''This year had quite a bad start in terms of reliability, which put us in a bad position,'' Vettel said.
Vettel has no victories this season and just four podium finishes. And he's considering not even driving in qualifying Saturday because a change to a sixth engine this season will force him to start from pit lane, regardless of how fast he goes.
His Red Bull run is almost over. Vettel has already announced he's leaving the team after this season but hasn't said where he'll drive in 2015.
''I'm looking forward the race, and to enjoy those last races I've had with the team. We've experienced a lot over the last few years,'' Vettel said.
The U.S. Grand Prix will have just 18 cars on the grid, the smallest F1 race in nine years. Two teams, Marussia and Caterham, have been sidelined with financial problems and won't race this week.
That prompted the FIA, the sport's governing body, to call Thursday for ''any initiative that will help reduce costs to ensure the survival of the existing grid and attract potential new entrants.''
