Fittingly, the last ever 250cc World Championship will be decided in the last ever race by the two-stroke class, at Valencia this weekend.

The series, which began during the inaugural year of motorcycle grand prix racing in 1949, is to be replaced by the new 600cc four-stroke Moto2 class next season.

The final title will go to either Hiroshi Aoyama or Marco Simoncelli, with Aoyama the overwhelming favourite due to a 21 point lead over reigning champion Simoncelli, with just 25 points still available.

Aoyama took a vital fourth win of the season for Scot Honda in the sweltering heat of Sepang, when a visibly drained Simoncelli wilted to third (after a photo-finish) for Metis Gilera.

Simoncelli, who failed to score in the first two rounds of the year, has won six races this year, but will need bad luck to strike Aoyama is he is to pull off a shock title defence before joining the Japanese in moving to MotoGP next season.

Some die-hard 250cc fans might have mixed feelings about the final 250cc championship going to Honda, a manufacturer that has all but abandoned the class in recent seasons and been a driving force behind the switch to Moto2 - when it will supply engines to entire grid).

But no-one can doubt Aoyama's worthiness, having performed wonders on a bike with little official development since Dani Pedrosa stormed to the 2005 crown.

"The maths says that we are in a good position, but the only figures that really count are the ones that you sum up after the last race," said Aoyama, ahead of the biggest weekend of his racing career.

"Do you want to know what my strategy will be? Easy: attack is the best defence. Sepang proved it," he declared.

The three other grand prix classes present during the inaugural 1949 season were 500cc, 350cc and 125cc.

Of those, only 125cc has survived unchanged with 500cc becoming MotoGP in 2002 and the 350cc class dying out at the end of 1982.