Goss and Renshaw were assisted by Brit Mark Cavendish and won the 51 kilometre even around the streets of Adelaide in a sprint.
"It's a great way to start the season with a win for the team," Goss said to the HTC Highroad Press office. "January has been really good to me. With the guys that we have here, we have so much strength, all I really had to do was sprint.
"Grabshi [Bert Grabsch] and Danny [Pate] did a great job bringing back the break and [Mark] Renshaw did the perfect job getting me and Cav [Mark Cavendish] into the right position."
HTC-Highroad had co-led the chase of four breakaways during the entire race, with Renshaw and Goss avoiding a big crash close to the finish.
"The plan was for Cav to sprint off Renshaw's wheel and for me to be on Cav's wheel to give us a couple of options. But on the last lap there was a crash and Cav had to brake a little, so I got onto Renshaw's wheel and he took me all the way to the line.
"Cav didn't go down and probably could have got back on the wheels, but he saw that a gap had opened so he left it open."
The Tour Down Under starts on Tuesday and you can see highlights plus some live coverage on Sky Sports 2&4.