By Alan Baldwin

ABU DHABI (Reuters) - Lewis Hamilton faces a moment of truth in Abu Dhabi this weekend.

The 2008 world champion has never finished a season behind a McLaren team mate since he entered Formula One in 2007 but that proud boast is set to end in the glare of the Yas Marina floodlights on Sunday.

Jenson Button is 38 points clear of his fellow-Briton, with only 25 left to win after the penultimate race of the year in the Emirate, and is on course to finish as overall runner-up behind Red Bull's double world champion Sebastian Vettel.

Beating one's team mate is every driver's immediate aim, since only he has exactly the same equipment and is therefore a true measure of performance, but it is not Button's top priority.

Button has taken three wins to Hamilton's two in a championship dominated by Vettel and Red Bull, despite the McLaren being close to their pace.

Vettel, 24, is the overwhelming favorite to chalk up a record-equaling 14th pole of the season on Saturday and then complete a clean sweep of three wins in the three Abu Dhabi Grands Prix held to date.


Hamilton and Button have both been on the podium in the previous two races in Abu Dhabi and the older Englishman sees no reason why they cannot topple Vettel from the highest step.

"Quite a few times this year, especially over the last few races, I have been the closest guy to Sebastian when he's won races," said Button, a winner most recently in Japan after Vettel had won there the previous two years from pole.

"It's a circuit that does suit their car," said the 31-year-old. "It's very stop/start and they seem to be very good at that type of corner.

"It is going to be tough to beat him (Vettel) and I would say out of the two (races left), (the season-ending race in) Brazil is the one that we have more of a chance of winning. but you never know."

Hamilton started on pole in Abu Dhabi in 2009 and then set the fastest lap last year on his way to second place.

"Red Bull and Sebastian may have clinched both championships, but I'm still determined to end the season on a winning high. I've won two grands prix this year, and I'd love to double that by the end of the year," said Hamilton.

Red Bull's Mark Webber will be happy with just one, the Australian still seeking that elusive first win of the season, while Ferrari's Fernando Alonso wants to put Ferrari on the Abu Dhabi podium for the first time.

Like Button, it matters far more to Alonso to win the race than to finish overall runner-up.

"I will not remember the 2011 season if I finish second or third," said Spain's double champion, currently third overall. "Once you are no longer in the hunt for the world championship win, the other positions are less relevant."

(Reporting by Alan Baldwin, editing by Justin Palmer)