Andrea Dovizioso of Italy (Ducati) poses after winning the Nero Giardini Moto-GP in Spielberg, Austria. (AFP/Erwin SCHERIAU) |
World championship leader Marquez had started on pole but Italian Dovizioso got the better of an incredible battle where the lead changed hands several times, including twice on the final bend.
Three-time world champion Marquez's Honda team-mate and compatriot Dani Pedrosa came third.
"I heard Marc's engine the corner before the last, he opened the gas before me, and I knew he wanted to try," said Dovizioso who saw Marquez slip past him on the final bend before the Spaniard ran wide and allowed the Ducati man to take back the lead.
"So I left the door open because if I didn't he would have hit me and could have won. He was good stopping the bike and trying to exit, but I was faster."
Dovizioso, who was second in Austria to his then Ducati team-mate Andrea Iannone last year, said the title race remains wide open.
"It was a stressful last lap but I'm happy with how we've worked throughout the weekend," he added.
"A lot of people expected us to win easily here, but the rules have changed. Everything is changing in this year's championship. Every weekend you have the chance to change everything, or lose a lot. There are five riders fighting for it."
Dovizioso's third win of the season moved him up to second behind Marquez in the standings, 16 points back, as Spaniard Maverick Vinales dropped to third after finishing only sixth.
That was one place above his Yamaha team-mate and seven-time world champion Valentino Rossi of Italy.
Marquez said he was proud of his desperate last-corner gamble as he stays on course for a fourth MotoGP world title with seven rounds left.
"Today on the last lap I was thinking about everything except the championship," he said.
"I pushed 100% and I decided to go all-in - the championship is important but even second place is. This year we were much closer but today Dovi, especially on the last laps, had a little bit more.
"But I got to the limit and I tried in the last corner because if not, I wouldn't have been able to sleep well tonight."
He added: "It was risky but I'm happy in the end because the 20 points are important. I was thinking about overtaking him in the penultimate corner but he closed the door and I'd had a few warnings there."
Dovizioso had started second on the grid but dropped to third as his Ducati team-mate and three-time world champion Jorge Lorenzo jumped from third to first at the start.
Dovizioso, who was second in Austria to his then team-mate Andrea Iannone last year, took advantage of the battle between Marquez and Lorenzo to snatch the lead.
Marquez also passed Lorenzo to launch his thrilling battle with Dovizioso.
The Spaniard seemed to have an edge in speed but every time he passed the Italian, usually after a daring and almost reckless lunge into a turn, his ice-cool rival quickly took back the lead.
Their battle allowed Pedrosa to close right in around six laps from the end but he couldn't challenge for the victory and Dovizioso prevailed.
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