Xaus will ride the all-new BMW S1000 RR next season
Spain's Ruben Xaus won the second World Superbikes race at Misano as Troy Bayliss extended his championship lead with two third-place finishes.
Ducati rider Xaus beat team-mate Max Biaggi into second place by 1.035 seconds, with Bayliss a distant 4.158 seconds behind after a late error.
Max Neukirchner, who won the first race, overtakes Honda's Carlos Checa into second in the championship.
The German is now 49 points behind leader Bayliss who has 259 points.
Checa, fifth in the first race, could only manage eighth place in race two and is 52 points behind Bayliss in third.
Neukirchner came through from a distant 10th place on the grid to beat Yamaha's Troy Corser into second place by 0.542 seconds in the first race.
He was well off the pace in qualifying but he roared back into form under race conditions to win his second World Superbikes race.
The second race had to be restarted on lap three after an engine failure for Honda's Karl Muggeridge left oil on the track.
On lap 15 Xaus made his move by overtaking Bayliss and two laps later he passed Corser, who finished fourth, to record his first win of the season.
Italian World Superbikes race one:
1. M Neukirchner (Ger) Suzuki 39 mins 27.918 secs
2. T Corser (Aus) Yamaha +0.542
3. T Bayliss (Aus) Ducati +2.249
4. R Xaus (Spa) Ducati +3.028
5. C Checa (Spa) Honda +5.408
6. L Lanzi (Ita) Ducati +5.518
7. J Smrz (Cze) Ducati +6.202
8. G Lavilla (Spa) Honda +18.279
9. S Nakatomi (Jap) Yamaha +19.072
10. N Haga (Jap) Yamaha +19.132
Race two results:
1. R Xaus (ESP) Ducati 39'19.710
2. M Biaggi (ITA) Ducati +1.035
3. T Bayliss (AUS) Ducati +4.158
4. N Haga (JPN) Yamaha +5.466
5. T Corser (AUS) Yamaha +6.759
6. L Lanzi (ITA) Ducati +13.468
7 M Neukirchner (GER) +15.221
8. C Checa C. (ESP) Honda +16.687
9. J Smrz (CZE) Ducati +17.030
10. F Nieto (ESP) Suzuki +17.681
Rider Standings: (after 8 of 18 rounds)
1. T Bayliss (Aus) Ducati, 259 points
2. M Neukirchner (Ger) Suzuki 210
3. C Checa (Esp) Honda 207
4 N. Haga (Jpn) Yamaha 191
5 T. Corser (Aus) Yamaha 185
6 F. Nieto (Esp) Suzuki 151
7 R. Xaus (Esp) Ducati 148
8 M. Biaggi (Ita) Ducati 117
9 M. Fabrizio (Ita) Ducati 111
10 R Kiyonari (Jpn) Honda 94