Marco Simoncelli took his first 250GP win in front of his home fans at Mugello on Sunday - but only after colliding with Hector Barbera at the start of the last lap, sending the Spaniard literally somersaulting along the main straight

Barbera had initially defended his pole position into turn one, but promptly ran wide, handing countryman Alvaro Bautista the lead from Simoncelli. Simoncelli clung to Bautista for the first six laps, but then - just as the Mapfre Aprilia rider was beginning to break away - he suffered a lowside from the lead.

That put Simoncelli at the head of his home grand prix by just one second from Barbera, with Thomas Luthi leading a six-man fight for third four-seconds further back.

Simoncelli resisted Barbera's pressure until lap 11 of 21, when the Spaniard's powerful Team Toth Aprilia rider slipstreamed effortlessly past Simoncelli's Metis Gilera to take the lead for the first time since the opening lap.

But Simoncelli, chasing his first 250cc victory, regained the advantage a lap later with a surprise move through one of Mugello's sweeping right-left chicanes. Barbera's next attack came with five laps to go and triggered a series of lead changes - and the start of some tactical riding - as the pair sized each other up for the final showdown.

The play acting came to a dramatic end when the pair slammed into each other along the main straight at the start of the last lap. Simoncelli appeared to swerve suddenly to the left just as Barbera pulled alongside to pass. Barbera's front end folded during the impact, sending the Spaniard somersaulting down the main straight on his 100th grand prix start.

Despite grazing the concrete barrier, a shocked Barbera was able to walk away without serious damage while Simoncelli was left to collect a controversial debut 250GP victory.

"I am the happiest person in the world! It is a fantastic to win my first 250 grand prix here in Italy," said Simoncelli. "The race was so difficult. In the first laps Bautista went very fast and it was very difficult to stay with him, but he made a mistake and I was able to take first place. With Barbera it was also a difficult battle. His engine was more powerful and in the last lap I tried not to give him the slipstream but he was so near that we touched."

Le Mans winner Alex Debon had taken third position from Luthi on lap 15, then signalled to the Swiss to tuck in behind rather than try to immediately retaliate, in the hope that they could work together to close the four-second gap to the leaders.

It didn't work and the pair were soon battling furiously for the final podium position once again - which then became second position after Barbera's heart-stopping exit. Debon just held off Luthi by 0.213secs, although the former 125cc world champion was still able to celebrate his first quarter-litre rostrum.

World championship leader Mika Kallio suffered a tough event, slipping from fourth on grid to tenth on the opening lap, but benefited from a series of retirements ahead of him to reach fourth at the flag.

Race results - Mugello:

1. Barbera (Aprilia)
2. Simoncelli (Gilera) +0.499secs
3. Luthi (Aprilia) +0.712secs
4. Kallio (KTM) +7.403secs
5. Pasini (Aprilia) +12.542secs
6. Locatelli (Gilera) +12.790secs
7. Abraham (Aprilia) +16.114secs
8. Aoyama (KTM) +17.316secs
9. Espargaro (Aprilia) +19.642secs
10. Wilairot (Honda) +19.704secs

13. Laverty (Aprilia) +47.422secs