AUSTIN - Sebastian Vettel can make his 100th Formula One race the United States Grand Prix an historic one here on Sunday by being crowned the youngest ever triple world champion. The 25-year-old German, and his Red Bull team, could make it a night for double celebrations if they take both the drivers' and teams' titles in a country where he made his debut as a baby-faced 19-year-old stand-in at Indianapolis in 2007.

That last United States Grand Prix, five years ago, was won by Briton Lewis Hamilton of McLaren and, this time around, he will once again be a major contender for victory in his penultimate race for the team before he leaves for Mercedes. But both championship leader Vettel and Hamilton know they face a challenge this weekend from two-time champion Spaniard Fernando Alonso of Ferrari who is 10 points behind the German in the title race and still convinced he can secure his own third title.

Finn Kimi Raikkonen of Lotus, victorious in Abu Dhabi, will also be a threat. Vettel, who replaced Pole Robert Kubica at BMW Sauber in 2007, managed to qualify seventh and finish eighth, his single point for that feat making him F1's youngest points-scorer -- a record that he still holds.

As he looked ahead to this weekend's showdown at the virtually unknown Circuit of the Americas, a purpose-built track 15 miles from Austin city centre, he admitted he could hardly believe it. "It's all gone so quickly," he said. "One hundred is a big number - 100 grands prix sounds a lot: 100 starts, 100 times surviving the first corner. If I reflect on it, it doesn't feel so long ago that I broke into Formula One...

"That shows me that time flies when you do something that you really like and enjoy, so let's focus on the second 100!" Typically, Vettel has not dwelt on the various permutations that could land him the title this weekend. He knows that with a 10-point lead he can secure the title with a victory this weekend and that is his clear goal. He goes into the race with two races -- worth a maximum of 50 points for two wins available -- remaining.

He has 255 points to Alonso 245. In spite of his extraordinary success in the last three seasons, there are many who still find it difficult to pour praise on Vettel and this week that list grew longer with the addition of 1997 drivers' champion Canadian Jacques Villeneuve.

The former Williams driver believes Vettel still has to mature and often "reacts like a child" if things are not going his way -- sufficient reason, for him, to be pledging his support to Alonso as the season reaches its climax. Villeneuve, however, said he felt that Vettel is almost invincible if he can lead a race from the front.

"These behaviours indicate two different states of maturity but, let's be clear, Sebastian is an ace too; however, he struggles more in critical situations. He looks almost unbeatable when he leads, but if he needs to catch up he becomes vulnerable." He added that he believed Vettel's stunning drive from the pit lane to a podium finish in third place in Abu Dhabi supported his view.

Vettel said he felt both he and Alonso were equally worthy of the title. "If you look at the races we've done so far I think Fernando's and my DNFs or calamities are equal," he told the official Formula 1 website. I still believe that the driver who deserves it most will be champion. No doubt we are in a very good position now and I hope we do well until the very end to make sure that we deserve the glory... Of course, the last races we had were very good for us, to put it mildly. They have helped us a lot."