The 2011 Superbike World Championship concludes at Portimao in Portugal this weekend, with only one major loose end to be tied up – the battle for third overall between deposed world champion Max Biaggi (Aprilia) and Yamaha’s Eugene Laverty.

Laverty currently holds the upperhand by just two points, but Biaggi, returning from injury after sitting out the last two rounds, is lighting fast at Portimao, having cleaned up in last year’s event.

The championship has already been won by Spain’s Carlos Checa (Ducati), with Laverty’s teammate Marco Melandri a certainty to finish second in his rookie year.

There will be four Australians riding at Portimao – Troy Corser (BMW), Mark Aitchison (Kawasaki), Josh Waters (Suzuki) and Karl Muggeridge (Honda).

For Corser, it’s his last ride on the S 1000 RR, with Melandri set to be the second factory rider at BMW Motorrad in 2012 alongside Leon Haslam.

There hasn’t been an official comment from Corser’s camp since the Melandri announcement, but Portimao could double as a farewell to the paddock he has been an integral member of for 15 years.

But it will be business as usual for the Wollongong flyer at Portimao, the three-year-old circuit which is much loved with its constant changes of elevation and fast, flowing turns.

“I like the Portimão track, and it will suit our RR,” said Corser. “However, there are a few crests over the hills where these strong bikes could pull wheelies. This might be our biggest struggle this weekend.

“I am really optimistic. To go fast in Portimão you need a bike that is steering well, and this is the case with our RR. It is an area that we improved with the chassis set-up and I was quite happy with the settings at Magny-Cours.

“We are aiming to find a similar set-up and the same feeling at Portimão. We will also try to improve the tyre life over the race distance. Then we should be well prepared.”

Waters, 24, will return to the WSBK grid for the third time this year on a Yoshimura Suzuki, after earlier guest rides at Phillip Island and Miller Motorsport Park in America. The 2009 Australian Superbike champion has scored points in three of the four races, with a best finish of 12th.

Despite a huge fall at Magny-Cours, NSW Central Coast rider Aitchison will line up at Portimao, while Gold Coast’s Muggeridge will deputise for injured Honda factory pilot Ruben Xaus.

It’s something of a homecoming for Muggeridge, who rode with the Dutch-based team from 2003-2006, winning the world supersport title in 2004. He now rides in the German Superbike series, where he was champion in 2010.

Meanwhile, Chris Vermeulen’s ill-fated two-year tenure with Kawasaki has already ended, with the Queenslander to miss the final round.

Australian Broc Parkes (Kawasaki) will finish third in the World Supersport Championship if he defeats teammate David Salom at Portimao.

And depending on how Fabien Foret (Honda) fares, Parkes could also seize second place off the Frenchman.

Briton Chaz Davies (Yamaha) already holds an unassailable lead.