SINGAPORE - Sebastian Vettel will be confident of extending his healthy lead at the top of the Formula 1 Drivers' standings in Singapore this weekend on a circuit that kick-started his imperious march to a third consecutive title a year earlier.In 2012 the German arrived in south-east Asia 39 points behind championship leader Fernando Alonso but drove a perfect race to capture the first of four-in-a-row wins as he sped past Alonso Spaniard in the second half of the season.A year on and the tables have turned with the Red Bull driver having a 53-point advantage over his Ferrari rival and carrying plenty of momentum to a circuit where he will be seeking a hat trick of victories.'CIRCUIT A KILLER'The Marina Bay Street Circuit is very much a Red Bull track; while Alonso remains hopeful of gaining ground on his title rival the reality is that Vettel is likely to head to next month's Korean GP with an even bigger lead."It's a very long race... the full two hours, it just seems to go on for ever," a cautious Vettel said earlier this week. "The circuit itself is a killer because there are so many bumps, there's no room for mistakes. It's one of the toughest of the year so to win is an amazing moment and you feel you deserve the Champagne."Alonso can, however, take heart from the fact that he too has won twice under the dazzling Singapore floodlights and claimed two more podiums and a fourth place since the race was added to the F1 calendar (flashback gallery!) in 2008. His Ferrari cannot match the Red Bulls' speed in qualifying but has shown a tendency to perform far better in races, with Alonso often cutting through the field from a mediocre position on the grid to challenge for victories.However, with only seven rounds of the 19-race season remaining, Alonso needs to add to his two 2013 wins or a third title will again slip from his grasp and leave the 32-year-old second in the standings for a third time since 2010.Alonso said: "It's a track I like and where I have usually gone quite well, getting four podiums from five starts, so again this year I'm tackling the weekend in a positive frame of mind, with great confidence that I can do well again."MERCEDES UPGRADESThe only other winner in Singapore, Lewis Hamilton, has made a smooth transition from McLaren to Mercedes through 2013 and he and team mate Nico Rosberg will be banking on improved performance from their cars to vie for victory on Sunday. Hamilton was unfortunate to miss out on a second Singapore victory a year ago when gearbox failur while he was leading from pole position all but ended his title ambitions. The 2013 challenge already looks over with the Briton a distant 81 points behind Vettel in third.Mercedes struggled at the low downforce tracks in Belgium and Italy but motorsport chief Toto Wolff feels there could be another shift in momentum as the team challenges Ferrari for second place in the standings. He said: "We expect the return to maximum downforce configuration to suit our car and we may see another shift in the competitive order between the teams."We'll bring new developments with the car once again for this race and we are all focused on maximising the opportunities for Lewis and Nico to re-establish ourselves in second position in the Constructors' standings."The tight, twisting circuit lends itself to driver errors and the pace car is often deployed - although it hasn't happened in the five previous Singapore GP's a seasonal downpour could have a huge bearing on Sunday's outcome. Thunderstorms are expected on Saturday.There will also be interest in Kimi Raikkonen's performance after the Lotus driver was confirmed as Felipe Massa's replacement at Ferrari for 2014, the Finn returning to the team for which he won the F1 championship in 2007. Stay with Wheels24 for the 2013 Singapore F1 GP weekend.