The closest World Superbike title fight since 2004 - and closest between two riders on different brands since the epic 2002 Edwards/Bayliss showdown - will be decided at Portimao on Sunday, when Noriyuki Haga and Ben Spies will fight it out for ownership of the 2009 crown.

Haga will start the event with a slender ten point lead over rookie Spies, but a double victory for Spies on Sunday - regardless of where Haga finishers - will hand the American his first and last WSBK crown before switching to MotoGP, and Yamaha's first ever title.

Over in the red corner, 2009 is Haga's tenth full season in World Superbike and he sits third in the all-time win list with 41 victories - but no world championship.

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To put that into perspective, world champions Scott Russell and John Kocinski only won 14 races during their whole career, while double world champion James Toseland needed only 16 race wins.

Despite less than a season in WSBK, Spies starts the Portimao finale just one win behind the career total of fellow Americans Kocinski and Russell. Spies has also overcome no less than five non-scores, the majority of which were out of his hands.

By contrast, Haga finished first or second in the first nine races of this season - his first with the factory Ducati team - but was injured at Donington Park (round nine) and finally lost the title lead to Spies at the Nurburgring (round eleven).

Many predicted the title battle was over, but Haga fought back and has beaten Spies - his replacement at Yamaha - in three of the last four races to set-up this weekend's showdown at the magnificent Portimao circuit.

The fight for the title is also likely to see some outside influence from the three other race winners this year.

One of those is two-time 2009 winner Michel Fabrizio, whose chief task at Portimao will be to assist team-mate Haga. At Magny-Cours the Italian was somewhat on the sidelines with two below-par races, but in Portugal he will be required to make a substantial contribution to the Ducati cause should it be required.

However no team strategy will be on the cards for the other two protagonists, Max Biaggi (Aprilia Racing) and Jonathan Rea (Hannspree Ten Kate Honda).

The all-Italian Biaggi/Aprilia combination has made considerable progress this season and Biaggi is now constantly in amongst the podium battle. To finish the season with another win would be a major boost for next season, when Max will expect to be one of the title candidates.

As for Rea, the young rider from Northern Ireland has proved himself to be one of the top riders in the category and he will surely be one of the favourites at a circuit where he made his WSBK debut just twelve months ago.

Biaggi and Rea will also be fighting for an overall fourth place, currently in the hands of Biaggi, who has a 14-point lead over his rival.

BSB champion Leon Camier, who will take the start for the second successive race on the Aprilia RSV4 machine, will be looking to impress the Italian team following his first outing at Magny-Cours.

The Noale manufacturer will enter three bikes, with Shinya Nakano returning for the first time since the Nurburgring.

Also searching for a place next year will be Britain's Shane Byrne (Sterilgarda Ducati), who may represent an outsider at Portimao.

In last year's pre-season testing he surprised everyone by setting the best time and will surely be looking to end this season on a high note - as will fellow Brit Leon Haslam, who starts his last weekend at Stiggy Honda before switching to Alstare Suzuki.

Just days after the 2009 season ends, a test session at Portimao will mark the start of preparations for the 2010 season - including an early debut for Haslam's team-mate Sylvain Guintoli in the Alstare team (in place of Max Neukirchner) and James Toseland's first ride on the R1.

The title is also still up for grabs in the World Supersport Championship, with Cal Crutchlow (Yamaha World Supersport) 19 points ahead of Eugene Laverty (Parkalgar Honda).

The English rider needs just a tenth place, irrespective of what his adversary does, to be crowned champion, before heading up to Superbike next year, when he will team up with Toseland in the official Yamaha squad.

As well as the Riders' title, Crutchlow will also have one eye on the Manufacturers' crown as Yamaha are just one point behind Honda.

There should also be a terrific scrap for third place as Kenan Sofuoglu (Hannspree Ten Kate Honda), the 2007 champion, will have to watch out for the talented young Kawasaki rider Joan Lascorz.

The Spaniard, all fired up following his splendid win at Magny-Cours, is just six points behind the Turk and will be looking for another top result to finish off his excellent season.