The 20-year-old Matthews, considered one of the peloton's most promising riders, finished ahead of last year's champion Andre Greipel and Goss after a 129-km ride from Unley to Stirling, south of Adelaide.

"It's unbelievable, Rabobank's Matthews told reporters.    "With one kilometer to go, I was on Matt Goss's wheel, an extraordinary position to be in and he made the mistake of attacking too early, 300 meters from the line.  

"In fact, I started believing in my chances when he sustained a puncture with 10-km to go. He seemed worried and I thought I had my chances. He came back but it didn't change how motivated I was."  

Goss, who won the first stage on Tuesday, had lost the orange jersey to Robbie McEwen a day later after he was involved in a crash that also included Mark Cavendish.   The British sprint specialist finished behind the main group, almost thirteen minutes off the pace.  

Meanwhile, retirement-bound American Lance Armstrong had a fairly uneventful day as the seven-time Tour de France champion came home safely in the bunch, more than three minutes behind the winner.   Friday's fourth stage is a 124-km run from Norwood to Strathalbyn.

In Johannesburg, Carla Swart, a South African cyclist who won several college titles in the United States, has died after being hit by a truck while training. She was 23.

Cycling South Africa says Swart died Wednesday during a training accident in Free State.

After dropping her cycling computer, Swart looked over her shoulder to check if the road was clear, and made a U-turn that put her in the path of the oncoming truck.

She had apparently looked over her left shoulder, as one would if cycling in the United States, instead of the right. In South Africa, vehicles drive on the left.

Swart moved to the US with her family as a teenager and attended Lees-McRae College in North Carolina. She had just joined the US-based HTC-High Road team.