SHANGHAI, Apr 28 (AP) -- Italian rider Valentino Rossi will seek to strengthen his lead in the MotoGP world championship standing when professional motorcycle racing's top event premieres in China this weekend.

Rossi brings a seven-point lead to the Chinese Grand Prix at Shanghai's International Circuit after winning the April 10 season opener in Spain and placing second in Portugal two weeks ago.

Running second is Brazilian Alex Barros of Honda, who won the Portuguese race and will be fighting to close the gap with Rossi.

Sixteen points behind the leader in third place is former 250cc world champion Marco Melandri who took third in Spain and fourth in Portugal. Italian Maxi Biaggi, who took third in Portugal, is ranked fourth in the standings.

One place behind Biaggi, Sete Gibernau of the Movistar Honda team, will seek a return to the podium after taking second in Spain and then crashing out in Portugal.

At least two of the sport's stars will be missing from the China event. Alex Hofmann of Kawasaki has been ruled out of the race with a broken wrist and will be replaced by French former 250cc champion Olivier Jacque. Makato Tamada, a two-time winner last season, is sidelined with a wrist fracture.

In the 250cc class, Australia's Casey Stoner, the winner in Portugal, will try to pull ahead of Dani Pedros, who took the win in the Spanish opener and leads by five points. Italian teenager Andre Dovizioso, second in Portugal, will also be battling to close the gap with Pedros.

Mika Kallio will seek a second straight victory in the 125cc class after squeaking past Spain's Hector Faubel in Portugal to become the first Finn to win a motorcycle grand prix in 30 years. That followed a second place finish for Kallio in Spain.