Haga, however, was slipping back rapidly as he continued to struggle with the handling of his Ducati Xerox on the drying tarmac. Dropping from sixth to tenth in just one lap, it was apparent the circuit was beginning to reach a stage where riders could switch to their slick-shod second machines.
First to take a punt was Shinya Nakano, who ditched his struggling Aprilia in favour of a new one at the end of lap nine, the Japanese rider becoming the man other teams would watch with great interest.
With Haga following soon afterwards, it kick-started a flurry of activity in the pit lane as riders switched machines, although it was Spies would be the first of the lead riders to go first.
Up to that point Spies had slipped to fifth position behind Checa, the Spaniard finding some remarkable speed to pass the American, Fabrizio and Smrz within two laps to move into second position.
With Fabrizio pitting on lap 13 – getting out in front of Spies on his return to the circuit –, Checa and Smrz followed on lap 14. However, Checa's chances were effectively ended when his Ten Kate Honda refused to fire up, leaving the visibly frustrated Spaniard to drop several seconds as his crew attempted to jump-start him down the pit lane. A similar problem had afflicted Rea earlier too.
Eventually Byrne pitted on lap 15 to emerge back on track in a provisional first place, with only Ruben Xaus
– yet to pit – ahead of him.
However, on a level playing field, it was Spies who was setting a remarkable pace, lapping considerably quicker than the riders ahead of him to dispatch of Fabrizio and Smrz quickly before destroying Byrne's advantage.
With the Sterilgarda machine seemingly unable to sustain the pace it showed in the damp, Spies simply drove around Byrne to take an effective lead.
Just a few seconds up the road, Xaus was leading for BMW, the first time the German brand has ever led a WSBK race. The Spaniard had been a marvel in slippery conditions, scything his way into contention having started in 18th position. He was pulling along Jamie Hacking and Leon Haslam too, who filled the top spots for a brief time as they attempted to make their waning rubber last as long as possible.
It didn't take long for Spies – lapping around ten seconds faster than Xaus – to relieve the BMW of the lead, moving ahead on lap 19 and simply romping away over the remaining five laps to claim another superb victory around a circuit he previously hasn't visited.