Brisbane, Jan 9 (DPA) Last autumn's knee injury looks to have been a deciding factor in Andy Roddick's decision to opt out of the US Davis Cup team for 2010.

The choice means that coach Patrick McEnroe faces a new challenge to select a squad for the World Group first-round tie on indoor clay in Belgrade March 5-7 against Serbia and Novak Djokovic.

Belgrade may also not be on the travel agenda for James Blake, another team stalwart, whose time on the squad stretches back to 2001 along with Roddick.

Roddick, seventh in the world and playing this week in Brisbane, said it was best for the team that they knew his intentions as early as possible.

"I'm not playing Davis Cup this year, (but) I'm not retiring from Davis Cup," said the 26-year-old. "I'm not going to be one of those guys who plays when it is convenient, when it is close to home and on a good surface for them.

"In Davis Cup you decide at the beginning of the year whether you are going to go through everything or not.

"Sometimes you have to listen to your body and do what is smart even though it is not an easy decision in the short term."

McEnroe will have to call on back-up players including Sam Querrey and John Isner to try and get the job done in hostile surroundings less than a fortnight after the end of this month's Australian Open.