LEAD: Hamilton, Button top practice as Vettel, Alonso skid out

Nov 11, 2011, 14:39 GMT

Abu Dhabi - Lewis Hamilton and Jenson Button led the way for McLaren on Friday in free practice for the Abu Dhabi Formula One Grand Prix while world champion Sebastian Vettel and ex-champ Fernando Alonso slid into the safety barriers at the same spot.

Hamilton topped the rankings with 1 minute 39.586 seconds on the 5.554km Yas Marina Circuit, with the morning session leader Button on 1:39.785 in the second stint from day to night.

Vettel skidded off the track at turn one and his Red Bull slid sideways into a safety barrier. Just minutes later Alonso suffered the same fate in his Ferrari at the same spot, with neither driver hurt and their cars not really damaged.

Vettel returned some 20 minutes later for a few more laps, but used a different setup and slower tyres which did not allow him to improve from sixth place in the list in 1:40.132.

Alonso was third in 1:39.971 from before his mishap, ahead of team-mate Felipe Massa (1:39.980) and Mark Webber of Red Bull (1:40.104).

Vettel claimed his first world title last year in Abu Dhabi when the race was the season-ender.

He assured himself of the 2011 crown three races ago in Japan but can still equal Nigel Mansell's season record of 13 pole positions if he wins qualifying on Saturday. Victory in Abu Dhabi on Sunday would also allow him to tie Michael Schumacher's 14 campaign wins at the November 27 finale in Brazil.

Vettel has not slowed down since clinching the title, winning the races in South Korea and India. He has also won both previous editions in Abu Dhabi.

Button's main objective will be holding on to second place in the 2011 standings, 13 points clear of Alonso, 19 ahead of Webber and 38 in front of Hamilton.

The 2008 champion Hamilton has had an indifferent season with two victories and several incidents, and is now in a fight to avoid finishing behind a team-mate for the first time in his F1 career.

Topping Friday's list will give Hamilton a boost, but times in practice are no full indication of a team's strength because the main aim is to get the cars ready for qualifying and the race.