The German won a bunch sprint at the end of stage four to give him 13 stage victories in the race and overtake Australian Robbie McEwen.
It was a second stage win this year for the Lotto-Belisol rider who comfortably beat Roberto Ferrari (Italy / Lampre), Jonathan Cantwell (Australia / Saxo - Tinkoff) and young Brit Andrew Fenn (Omega Pharma - Quick-Step) to the line at the end of the 126.5km stage from the Adelaide suburb of Modbury to the Barossa town.
But a mass pile-up inside the final kilometre saw Graeme Brown taken to hospital with a suspected broken hand and Bernie Sulzberger suffering a suspected broken finger.
Belgian road race world champion Philippe Gilbert and young Australian Damien Howson were involved in the break of the day but their maximum advantage was three minutes and they were caught with six kilometres left.
Team Sky’s Geraint Thomas retains his five second overall lead from Tom-Jelte Slagter (Netherlands / Blanco) with two stages remaining.