AUSTIN, Texas (AP) -- Four-time world champion Sebastian Vettel served notice Friday he has every intention of going after a victory that eluded him last year and perhaps set a couple of records are still within reach during his remarkable season.
Vettel posted the fastest time in the day's two practice sessions at the U.S. Grand Prix, driving the Circuit of the Americas in 1 minute, 37.305 seconds, topping teammate Mark Webber for a 1-2 start for Red Bull on the first day of driving.
It was quite a turnaround from the morning for Vettel, who finished a leisurely 18th in the first practice that was delayed by fog, then stopped and ultimately shortened to about half of its scheduled 90 minutes.
Vettel led most of the 2012 U.S. Grand Prix only to lose it to Lewis Hamilton with just 14 laps to go. Like Hamilton did last year, the German driver wore the stars and stripes of the American flag on his helmet Friday.
''We're pretty fired up,'' Vettel said heading into Saturday's qualifying. ''It was really close last year. I like this circuit ... I think we can be quite happy.''
For Webber, Friday's strong performance is yet another reminder of what he can still do - and what's eluded him - in his final season in Formula One. Webber is leaving the series after this year to join Porsche for the world endurance championship.
Webber has started four races either in pole position or No. 2 this season, but has yet to win while Vettel has dominated the field with 11 victories. Vettel has won seven races in a row and another this week would set a single-season record for consecutive victories. Win the last two races of the season and Vettel will tie Michael Schumacher's record of 13 in one season.
Webber started on the pole in two of the last three races and finished second both times.
''He destroyed us'' in the races in Japan and Abu Dhabi, Webber said. ''It would be nice to get a good result here.''
Neither Red Bull driver had much to show in the early session that was delayed for 40 minutes by fog, then interrupted for about 15 minutes when race officials pulled the drivers off the track because the medical helicopter hadn't arrived.
Ferrari's Fernando Alonso had the fastest time of what was left of the morning session with a lap of 1:38.343.
It was an impressive drive for Alonso, who has complained of a sore back since he was forced off the track to avoid a crash in Abu Dhabi two weeks ago. Alonso wore support tape on his neck and shoulders that was visible above his collar on Friday.
The 2005 and 2006 world champion hasn't won since the Grand Prix of Spain in May, but is virtually assured of a second consecutive second-place finish in the driver's championship behind Vettel.
With a maximum of 50 points still available, Alonso is 34 points ahead of Lotus's Kimi Raikkonen, who is not driving the final two races after having back surgery. Alonso has a 42-point lead over Mercedes' Lewis Hamilton.
The morning interruption caused a problem for McLaren's Jenson Button, who was second-fastest in the session but was hit with a three-place penalty in Sunday's starting grid because he passed another car when the red flag was out.
The penalty was the latest blow in a season of disappointment for the historically powerful McLaren team, which has yet to earn a podium finish this year.
''It wasn't dangerous. I didn't do it on purpose but the rules are the rules,'' Button said. ''We can't change that now. It was my mistake. It's frustrating, because I haven't made it easy for myself the last couple of races.''
The helicopter had been delayed by the fog and Formula One prohibits racing without it. A spokesman for the FIA, the sport's governing body, said he didn't know why the session was allowed to start before the helicopter arrived. Because fog could be a problem again Saturday morning, track officials plan to keep the helicopter at the circuit overnight.