The Aussie international has been given special permission by boss Kevin Blackwell and will miss the first few of United's opening games.
Blackwell initially didn't want to let Carney participate in the Olympics set to start next Friday but has allowed the 24-year old to jet off to China.
Blackwell said: "I have had the Australian Olympic people on to me every day wanting Dave to be available to them and I kept saying no because I wanted him to be part of things here.
"But it relented in the end because I thought it would give him good exposure and the chance to play games. Australia are in a very tough group which might help him catch up in terms of fitness and match sharpness."