The Spaniard was making good progress from an early eighth place and was soon with the Suzuki pair of Fonsi Nieto and Kagayama. These two were soon dropped by the leaders though and though Kagayama was able to hold on for a solid placing, they were both soundly beaten by the impressive Neukirchner.
Up front the game of cat and mouse was beginning. Haga was able to stay with Bayliss for a few laps before the Ducati started to just edge clear bit by bit. Then with nine laps to go Bayliss pushed away again and the threat from the Yamaha favourite seemed over.
As this was all going on the battle for the remaining podium place was heating up. Neukirchner was in that place with Xaus right there as the pair of them slowly dropped away from Bayliss and Haga.
The Spaniard made a very good move on Neukirchner in the twisty section on the older part of the circuit, and edged away from the Suzuki.
Catching them both though was Checa, he pushed inside Max at the final chicane and on the last lap managed to get past Xaus into the new turns after the start/finish straight to nick second.
As all this was going on, in the lead Bayliss seemed to be in control but Haga simply refused to give up and on the last two laps was right with his old rival.
The Yamaha looked quicker in only a few places though and despite Haga making a very strenuous effort to get past out of the final corner Bayliss was able to score a superb double win on his last visit to Assen.
Behind the top five were some great rides. Gregorio Lavilla yet again raced like the champion he was in the UK and managed to get seventh place from the equally impressive Jakub Smrz in the final few laps.
Positive results for Paul Bird's team and Lavilla's bike was among the very fastest through the speed traps all weekend.
Kawasaki should be very pleased with Makoto Tamada's results, the former MotoGP man scored two top ten results and looks much happier in his new home.
Karl Muggeridge raced well on his DF Honda to be only a few seconds away from the admittedly still clearly injury troubled Max Biaggi in 13th.