Gerrans, who also won Thursday's third stage in a sprint, has the advantage going into the fifth stage, a 151.5-kilometre stretch from McLaren Vale to Willunga Hill on Saturday.

"I'm absolutely thrilled with that," the 35-year-old said while thanking his team for making his run "as easy as possible".

Gerrans, the overall winner of the Tour Down Under in 2006, 2012 and 2014, will be hoping experience pays off when it comes to Willunga Hill.

But the Orica GreenEdge leader is taking nothing for granted, having been caught in a mass pile-up inside the final kilometre of Wednesday's stage just after putting himself in a perfect position to take the stage win.

"I still have to be very, very attentive going into Willunga tomorrow. We have a nice little buffer there, but there's still a heck of a lot of work to be done," he said.

Gerrans crossed the line Friday in three hours, 13 minutes and 59 seconds ahead of English Sky rider Ben Swift and Italian Giacomo Nizzolo (Trek-Segafrefo) who were both credited with the same time.

In the general classification, Gerrans (13:41.58) leads fellow Australians Jay McCarthy (+14 seconds) and Rohan Dennis (+26).