Geraint Thomas lost the leader's ochre jersey at the Tour Down Under as Orica GreenEDGE's Simon Gerrans won stage five up Old Willunga Hill.
Great Britain Olympian Thomas is now fifth in the general classification, 29 seconds adrift of new leader Tom-Jelte Slagter who has a 13-second advantage over second-placed Javier Moreno.
Dutchman Slagter broke clear of Thomas in the final kilometre to challenge for the line - but Australia Day belonged to a home team and rider in Orica and Gerrans, who held on to take the stage win and with it a 10-second time bonus.
The six seconds earned by 23-year-old Slagter, though, lifted the Team Blanco ahead of the pack and into a commanding position in the race for the overall title.
Thomas told Sky Sports 1: "My legs just went with about 500 to go. I just went backwards and lost the whole thing.
"I was giving it everything but nothing was coming out.
"But it's only the first race of the year, we started with a bang and ended with the wrong kind of bang, but it's been a good week."