Marco Melandri took the first race victory of 2018 at Phillip Island on his Ducati Panigale, ahead of Tom Sykes and team-mate Chaz Davies.
Melandri ran third in the early stages behind the two factory Kawasakis after a good start but came alive during the closing stages.
He first picked off reigning champion Jonathan Rea for second with a third of the race remaining and then set about chasing down poleman Sykes for the lead.
The Italian relentlessly closed the gap and blasted past Sykes on the start/finish straight with a few laps to go. Melandri then opened up a lead of around a second, maintaining this as he crossed the line 1.1s ahead of Sykes to become the first rider other than Rea to lead the championship since 2014.
Chaz Davies struggled to match the pace of his team-mate, only overtaking the independent Barni Ducati of Xavi Fores with a few laps remaining.
Rea’s race took a turn for the worst when his Kawasaki ran into a tyre problem in the last couple of laps, losing around two and a half seconds a lap to the leaders.
Davies duly moved ahead of the stricken Rea on the penultimate lap, Fores following through for fourth and leaving Rea to salvage fifth.
Yamaha’s Alex Lowes was too far behind to catch Rea, but came out on top in a dogfight with team-mate Michael Van der Mark, the two going side by side for nearly a lap before Lowes eventually made the move stick and pull away.
Van der Mark had a race of two halves, charging in the middle stages and moving ahead of Davies, before the Briton moved back ahead and the Yamaha dropped back.
The Dutchman lost out to the charging Honda of Leon Camier and Eugene Laverty’s Aprilia respectively to take ninth at the flag, while Leandro Mercado rounded out the top ten.
Fores, therefore, will start on pole position for the reversed-grid second race tomorrow, sharing the front row with Rea and Lowes.