The Suzuki star and defending World Superbike champion managed to fend off a determined Troy Bayliss to win at the Losail track.
The all-Aussie scrap, which saw Bayliss reel in Corser and have two serious attempts at passing him on the final lap, has raised hopes of a similar showdown at the Australian World Superbike Championship round at Phillip Island at the weekend.
But Bayliss came away from the Qatar round with the most points.
The former MotoGP rider finished second in both races, while Corser was fourth in the opening race before winning the second.
Bayliss, who clearly enjoyed dicing for race wins again after three tough years in the MotoGP class, made a last-corner lunge to pass Corser.
Bayliss said: "It was a good hard fight, but my timing was a bit off on the last corner. Congratulations to Troy."
It was a tough race for Bayliss, a former World Superbike champion, who had to make up for a poor start.
"I found myself in fourth or fifth after the start and I just had to put my head down and give it everything I had," he said.
Corser, keen to make up for finishing race one off the podium, fought his way through to lead on lap five and built up a healthy margin.
The Suzuki rider said, as Bayliss caught him, he had to adjust his clutch as he rode to try to stop it from slipping.
"I knew someone was behind me and I could hear the bike, but I was still trying to fix the clutch," Corser said.
"I think I was a bit lucky to pass Troy on the last lap because he went a bit off track.
"There was a bit of fortune, a bit of mistake and a bit of luck. That's racing, I guess."
Britain's James Toseland managed to hold off a hard-charging Bayliss in race one to take a surprise win.