Bayliss, 38, plans to retire at the end of the season

Bayliss held off fellow Ducati rider Max Biaggi in the final lap of race one in Doha, while Troy Corser was third.

Fonsi Nieto, riding a Suzuki, claimed his first championship win in race two, with Ducati's Ruben Xaus second.

Bayliss, who plans to retire at the end of the season, leads the table on 38 points, two ahead of Italy's Biaggi.

Germany's Max Neukirchner dominated the first half of the first race at the Losail International Circuit, with Corser, who had started in pole, and Japan's Noriyuki Haga in close pursuit.

But Haga crashed spectacularly on the seventh of the 18-lap race as he tangled with Biaggi in a battle for third.

After the restart, Bayliss moved through the field to overtake Neukirchner for the lead with 10 laps to go, but the Australian went wide a lap later and dropped back to fourth.

Biaggi took over the lead as Neukirchner faltered but double Superbike champion Bayliss roared back and overhauled Biaggi twice on the final lap to win.

Corser, who started both races on pole, finished third with Spaniard Ruben Xaus fourth and Neukirchner fifth while Haga remounted to finish with two points in 14th.

In the second race, Spaniard Nieto clocked a best lap time of 1 minute, 59.156 seconds as he powered home to victory.

World Superbikes Championship, Losail, Qatar: Race 1 result:

1. Troy Bayliss (Aus) Ducati 36 mins, 11.468 secs
2. Max Biaggi (Ita) Ducati +0.396 secs
3. Troy Corser (Aus) Yamaha +1.878
4. Ruben Xaus (Spa) Ducati +4.487
5. Max Neukirchner (Ger) Suzuki +7.505
6. Carlos Checa (Spa) Honda +9.639

Race 2 result:

1. Fonsi Nieto (Spa) Suzuki 36 mins, 12.963 sec
2. Ruben Xaus (Spa) Ducati + 0.301 secs
3. Max Biaggi (Ita) Ducati +1.321
4. Troy Bayliss (Aus) Ducati +6.452
5. Michel Fabrizio (Ita) Ducati +7.627
6. Lorenzo Lanzi (Ita) Ducati +9.117