'Job done' as Francesco Bagnaia wins Italian MotoGP sprint race
The Ducati star capitalised on his record lap time to secure pole in qualifying earlier to beat Marco Bezzecchi and Jorge Martin.
Bagnaia now has a four-point lead over Bezzecchi, riding for Italian legend Valentino Rossi's VR46 team, going into Sunday's sixth round of the championship.
Bagnaia, nursing an ankle injury from his crash last time out at Le Mans, led from Marc Marquez but Jorge Martin nabbed the lead at the end of the opening lap.
Alex Marquez, who set off in third, lasted only as far as turn one when he slithered out of contention on the gravel run off.
As rain drops began to splatter on Ducati's home circuit Bagnaia regained the lead with eight of the 11 laps remaining.
Under ominously dark clouds Bagnaia was being hunted down by Bezzecchi, who came into this weekend just one point adrift in the championship standings.
Bezzechi, who started back in seventh, kept up the fight on his compatriot and friend but Bagnaia had the race in the bag, to the delight of his legion of fans.
"It was a bit scary at the start and had to be careful not to panic with the rain, but my pace was good. I really enjoyed the day - Mugello is beautiful," said Bagnaia after his third sprint success of the season.
"Job done today!" he added.
Now he goes in search of a third race win at a track where he won 12 months ago.