Line-astern lap after lap, Bayliss was back through at the final turn on lap 12 when Haga ran ever so slightly wide, before resisting his attempts to come back at him straight afterwards.
The pair weren't done yet though, Haga passing again on lap 15, but while Bayliss dipped beneath him at the hairpin, Haga switched back up the inside to re-take it.
With Corser third, Bayliss needed to win to secure the title, as second place fell just one point short of what he needed for victory on Ducati's home turf.
However, his cause was being aided by team-mate Fabrizio, the Italian having battled his way up to fourth before putting in a series of superb lap times to catch Corser with only a couple of revolutions to go.
By this point, Haga and Bayliss had passed and re-passed each other again, but Fabrizio's crucial pass on Corser coming down the back straight on the final lap was all Bayliss would need to call himself champion once again.
However, this was unbeknown to him and as he continued to push over the final few bends, the bike came away from him at the slow hairpin, sending him crashing to the ground. A surprising end to what had been a stunning head-to-head between himself and Haga, Bayliss got going again but would cross the line 16th and out of the points.
As a result, Haga crossed the line for his second win of the day and his sixth victory of the season, a result that even keeps him in with a shout of the title.
Corser's third place, behind a jubilant Fabrizio, ensures that he remains Bayliss' closest competitor, although the 79 point gap between himself and his countryman means the title remains very much in Bayliss' hands.
Beyond the excitement going on at the front of the field, Max Neukirchner came home with his second fourth place finish of the day, which means he too can still mathematically win the title.
Carlos Checa also made it a double fifth place just behind, ahead of Alstare Suzuki duo
Fonsi Nieto and
Yukio Kagayama, the team enjoying a better day than of late.
