He was joined on the podium in a Yamaha 1-2 by 3C Racing and fellow Italian Manuel Monni, who collected a GP trophy for the second time.

"I could not expect this victory after my injury last week. I hit my shoulder on a pole in a silly crash and I have torn a ligament. The doctor said that maybe it was not possible to race here. I tried on Saturday and did OK but I had a lot of pain. I had an injection for Saturday and also Sunday and the shoulder, luckily, was not so bad. The conditions were terrible however and so many riders stopped, but I had a good start and rode within myself. I am so happy with this win because I have had some bad luck with injuries at the start of a few seasons. I just want to run with the leaders at each Grand Prix and look as high as I can in the championship."

After a warm and sunny day of practice and qualification on Saturday (in which Guarneri took fifth position in his heat race thanks to painkillers) constant rain from the early hours of Sunday turned the track into a bog of deep ruts and slippery mud.

Riders fell numerous times and many were forced to retire as the conditions worsened and swallowed machines that veered too far off course. The track was so wet that the lines altered almost every lap.

After a fine 3rd spot in Moto1 Guarneri fronted the dispersed pack for much of the second half of Moto2 after team-mate Nico Aubin also took a turn as leader.

Like almost everyone the Italian also fell-foul of the track in the closing stages but due to the quantity of riders stuck on the steep step-ups the race was stopped with one lap to go and thanks to a advantage of almost three minutes Guarneri was declared the winner and overall victor.

Monni - Guarneri's main rival for the Italian MX Championship - was second when the race was red-flagged and with his 6th position in Moto1 was able to celebrate his first taste of podium champagne since the German Grand Prix in 2005.