Nursing a cracked scaphoid bone in his right wrist, the 16-year-old from Kurri Kurri, New South Wales, pushed his way through the world-class field from last place to score another 10 world championship points.

"It feels great to finish sixth after all the problems we had in final qualifying (when he was only 18th, although his first session time left him 13th on the grid)," Stoner said.

"I completely messed up the start by getting the bike too hot and ended up in last position. I then had to ride very hard to make up positions and lost touch with the lead group.

"I slowed down for a while and then saw the group in front slowing, so I pushed harder and was able to catch and pass them.

"The last three laps I had to push myself to keep going as riding so hard in the heat completely destroyed me.

"The bike set-up was really good and my injured wrist gave me few problems."

It is the second time Stoner has finished sixth in his 250cc debut season riding for the Italian-run Safilo Oxydo Race LCR team. He became the youngest rider to score points in the 250cc world championship when he finished sixth at another Spanish circuit, Jerez in the country's south-west, in the third race of the season.

Italian Marco Melandri took his third 250cc victory of the season in Barcelona in front of compatriot Roberto Rolfo and Spain's championship leader Fonsi Nieto.

Manuel Poggiali from San Marino took his second straight win on his Gilera in the 125cc class by just 0.019 seconds ahead of Spain's Daniel Pedrosa on a Honda. Third-placed German Steve Jenkner was almost 10 seconds behind championship leader Poggiali.