MotoGP machines haven't ridden at Estoril, venue for round three of 18, since last September - when Dani Pedrosa, currently leading the MotoGP World Championship for the first time ever following his Jerez victory, finished a close second to Valentino Rossi.

Due to delays with the '08 Repsol Honda engine, Pedrosa's spring-valve powerplant hasn't been substantially changed since that race - and is thus tipped to suffer along the Estoril main straight this weekend - but the Spaniard has already defied a pre-season hand injury and set-up issues with the RC212V to take third and first in the two opening rounds.

Rossi hasn't won a race since that September victory, but returns fresh from a best-yet second place on his new Bridgestone tyres and hoping it'll be a case of third time lucky for his new tyre partnership. Victory for the Italian would also end a six race losing streak - at a circuit Rossi has already won at five times in the premier class.

Between Pedrosa and Rossi in the championship standings sits The Doctor's Fiat Yamaha team-mate and MotoGP star rookie Jorge Lorenzo, who lurks just five points behind arch-rival Pedrosa after a dramatic start to his premier-class career.

Lorenzo has taken two pole positions and two podiums from his first two MotoGP events, but - like Pedrosa - has never previously won at Estoril in any class. Being a rookie, Lorenzo will also face the additional challenge of 'relearning' the bumpy layout on an 800cc machine.

But the man to beat could well be world champion Casey Stoner, fired-up to reassert his authority after a Ducati-worst eleventh at Jerez and having finished a close third in the 2007 Estoril race - despite a clutch problem. The 22-year-old Australian is just one point behind Rossi in the points and won the 250cc race in Estoril three years ago.

Andrea Dovizioso took 250cc victory at Estoril two years ago and, while yet to join fellow rookies Lorenzo and James Toseland in claiming a top three performance in either qualifying or a race, the JiR Team Scot rider sits a strong fifth in the points - despite finishing eighth in Jerez after a frantic last bend encounter with Loris Capirossi, Toseland and John Hopkins.

Two sixth place finishes for Toseland have placed the reigning double World Superbike champion just one point behind 'Dovi'. The Tech Yamaha rider doesn't have prior knowledge of Estoril, but will be in a much better physical state this weekend - after battling bronchitis at Jerez - and will make his much-anticipated debut on the latest pneumatic-valve Yamaha engine.

Former world champion American Nicky Hayden achieved his best ever Estoril finish with a fourth place last year - from pole position - at a track where his 2006 title dream looked to have been shattered by an infamous clash with team-mate Pedrosa.