Singapore: Sebastian Vettel will retain the Formula One drivers` world championship title this weekend if he finishes the Singapore Grand Prix with a lead of at least 125 points over the chasing pack.
To clinch his second title, Vettel must increase his lead over closest rival Fernando Alonso from 112 points to 125 and enlarge his 117-point lead over Jenson Button and Mark Webber to the same margin.
If Alonso finishes on the podium, in any position, or if Vettel is beaten by any of his rivals, the championship will not be won in Singapore.
He also has to keep his 126 points lead ahead of Lewis Hamilton, or at worst not let it slip by more than one point.
There are a number of scenarios in which the German driver can clinch his second title including if he wins and Alonso finishes outside the top three -- and both Button and Webber fail to grab second spot.
In the current standings, Vettel has 284 points (and has won eight races), Alonso has 172 (one win) while Button (two wins) and Webber (no wins) have 167. Hamilton (two wins) has 158 points.
The points system is: win - 25 points, second 18, third 15, fourth 12, fifth 10, sixth - eight, seventh - six, eighth - four, ninth - two and 10th one point.
After Singapore there are five races remaining.