The 2009 F1 World Championship campaign is closing in and the title battle is hotting up - but it could all be resolved as soon as this weekend's Japanese Grand Prix, should Jenson Button prove capable of rediscovering his devastating early-season form around what is inarguably one of the few remaining true drivers' circuits on the calendar.

Following a two-year hiatus whilst the race moved to Fuji Speedway, the Japanese Grand Prix returns to Suzuka this year, and for the foreseeable future, much to the approval of the top flight's drivers, teams and fans alike, all of whom recognise the demanding Honda-owned track as a genuine test of bravery and skill, where only the great prevail. Of the current grid, only Rubens Barrichello, Kimi Raikkonen and Fernando Alonso have triumphed there - and a similar result for the former this weekend could potentially blow the duel for the crown wide open.

Singapore aside, there is little doubt that it is the Brazilian half of Brawn GP's driver pairing who has performed better in recent races, notching up 34 points from the last seven outings to Button's 23, and invariably both out-qualifying and out-racing the long-time world championship leader, whose advantage in the drivers' standings began to look shaky indeed over the summer months. Though that margin has largely stabilised lately as none of the British star's chief rivals have proven able to strong a consistent run together, Button is well aware that just one slip-up or mechanical failure could reduce his lead to just five points heading into the final two grands prix. The 29-year-old can actually seal the deal this weekend if he succeeded in out-scoring Barrichello by five points or more, but given that has only happened on two occasions this season - and not at all since Turkey in early June - and the fact that it is the rejuvenated S?o Paulista who has the better record of the two at Suzuka, the title tussle looks likely to go on to at least Shanghai if not all the way to the bitter end.

Off the back of a succession of off-colour performances and dubious reliability, Red Bull Racing's bolt now looks to be shot in terms of world championship glory, with N?rburgring winner Mark Webber officially out of the reckoning following his Singapore brake failure, and team-mate Sebastian Vettel lying a full 25 points adrift of Button - and therefore mathematically looking likely to be similarly knocked out of contention this weekend, particularly if his Renault engine lets the young German down again. Saying that, Suzuka is a track whose nature - much like Silverstone, where nobody else could touch Vettel and Webber - should suit the Adrian Newey-penned RB5 down to the ground, and F1's youngest-ever winner will doubtless relish the challenge that the circuit offers. Should the energy drinks-backed outfit notch up another one-two and Brawn find itself demoted by an interloper or two, RBR could yet provide an unpleasant sting in the tail for its Brackley rivals between now and season's end.

The most likely 'interlopers' capable of spoiling Brawn's weekend are Ferrari, McLaren-Mercedes, Renault and Williams. Despite the Scuderia's poor Singapore form - where neither Kimi Raikkonen nor Giancarlo Fisichella were able to trouble the scorers in a race in which twelve months earlier Felipe Massa had dominated early on - the F60 is tipped to be much more at home at Suzuka, where the 2007 world champion in particular has always shone, famously pinching victory from his current team-mate in the 2005 Japanese Grand Prix barely a lap from the chequered flag. The Maranello-based outfit is presently locked in a tense squabble over third spot in the constructors' standings with traditional rivals McLaren, though the Woking-based concern's managing director Jonathan Neale is pessimistic as to the team's chances in Japan, mindful of the low downforce-shy MP4-24's abject showing at Silverstone just over months ago and the fact that reigning F1 World Champion Lewis Hamilton has never raced there before. This weekend, he acknowledges, will very much be a litmus test for the multiple world champions' progress in recent weeks.

Renault put the 'Singapore-gate' scandal behind it in the best fashion possible in Singapore, though Alonso somewhat tarnished his superb podium performance with a public post-race dedication to the Enstone-based operation's disgraced former managing director Flavio Briatore - for which the Ferrari-bound Spaniard might yet find himself in hot water with the powers-that-be at the FIA, who are understood not to have been much amused by what they viewed as his misplaced loyalty. Nonetheless, the Oviedo native is the defending race-winner in Japan, and can always be counted upon to shine there - but the grand prix could prove to be something of a baptism of fire for young rookie team-mate Romain Grosjean, who will be making his Suzuka bow.

Williams, meanwhile, lost out big-time in Singapore when Nico Rosberg accidentally overshot the pit-lane exit following his first stop, costing the inspired young German a certain rostrum finish and possibly even a shot at victory into the bargain. The 24-year-old will doubtless be eager to atone for his error this weekend, and should find Suzuka very much to his liking indeed.

As to the remainder of the grid, BMW-Sauber is seeking a respectable end to what has been a largely desultory final season at the highest level - with the lower end of the points about the best Nicki Heidfeld and Robert Kubica can feasibly hope to aim for - whilst Force India F1 will be bidding to return to the form displayed at both Spa and Monza following the dramatic Singapore slump. Toyota may be on home turf, but the big-budget Japanese manufacturer's form is impossible to predict from one weekend to the next given the TF109's frustrating inconsistencies - meaning a repeat of Ralf Schumacher's 2005 pole position is not out of the question, but then neither is a failure to progress beyond Q1. Scuderia Toro Rosso, finally, look happy merely to get a dispiriting campaign done and dusted and move onto next year - but before then, of course, F1 still has a new champion to be crowned...'s Tip for the Top: Sebastian Vettel's One to Watch: Fernando Alonso