Armstrong happy to finish in peloton
The seven-times Tour de France champion, taking part in his last international race overseas before ending one of the most amazing careers in cycling, finished safe in the bunch after a 138-km ride from Mawson Lakes.
"The beginning of the stage was fast but everything went well for him," RadioShack team manager Johan Bruyneel said.
"He still belongs to the peloton."
Armstrong, his face dripping with sweat, left in a private car to join his partner Anna Hansen and his two youngest children, Max and Olivia.
"It's a tough race. Not because of the course but because of the pace set by the sprinters' teams," Armstrong said before starting the stage.
"Within my RadioShack team, we have Robbie McEwen, who is as motivated as a new pro. Me? I'll do my best."
Australian McEwen, who at 38 has 12 Tour de France stage wins to his name, came home third behind HTC-High Road's Goss and German Andre Greipel of Omega Pharma-Lotto.
"(...) a good result for @TeamRadioShack! No racing for 5 months = suffering!" Armstrong said on his Twitter feed.
Armstrong came out of retirement in 2009 bidding for a record-breaking eighth Tour de France title. He finished third overall in 2009 but could only manage 23rd last year.
Wednesday's second stage of the Tour Down Under is a 146-km ride from Tailem Bend to Mannum.