Jonathan Rea took his fifth victory of the 2019 season in very wet conditions, as championship rival Alvaro Bautista made yet another mistake.
The Kawasaki rider was in a league of his own in front of the home crowd, as he hit the front from lap one and never looked back.
Rea immediately set about creating a gap, with the Pole man Tom Sykes in second and teammate Leon Haslam in third.
It was evident from the opening laps that the battle was for second place, as Loris Baz closed down the two Brits on the Ten Kate Yamaha.
At the mid point stage of the race, Bautista was in fifth with Alex Lowes a further second back. But the Aruba.it Ducati rider crashed out at Starkey’s Bridge with a big highside resulting in the championship lead changing for the first time this season.
Only two rounds ago, Bautista had a lead of over 61 points. However the Spaniard now trails the four-time champion by eight points going into Sunday’s crucial double header.
Rea went on to win by a commanding margin of eleven seconds, ahead of Sykes who matched his best result of second in Misano.
Both second place finishes for Sykes this season have come in extremely wet conditions, but the Donington Park specialist will be hoping for a dry race on Sunday given his pace in free practice.
Haslam took third ahead of Baz, completing his best result in a race since the opening round at Phillip Island, Australia.
Lowes was fifth for Pata Yamaha, while Leandro Mercardo produced his best ride of the year to take a well deserved sixth place.
Seventh was the second BMW of Peter Hickman, who was competing in just his third ever World Superbike race. Eighth was Michael Van Der Mark, who made the biggest gain of the day after starting from sixteenth place on the grid.
There was also a first top ten of the year for Honda rider Alesandro Delbianco. The Italian is no stranger to the wet conditions and made a late move on Chaz Davies who rounded out the top ten for Ducati.
