The United States begins defense of its Davis Cup tennis title this week when it takes on Austria in a World Group first round series indoors on clay in Vienna.

American Andy Roddick will play the opening singles match against Jurgen Melzer with James Blake taking on Stefan Koubek in the second match Friday.

The Bryan twins - Bob and Mike - will play Melzer and Julian Knowle in doubles Saturday. The reverse singles are Sunday.

Meanwhile, Australian Open champion Novak Djokovic of Serbia leads his team against Russia on hard courts indoors in Moscow. Djokovic, who captured his first major tournament title last month in Melbourne, faces Mikhail Youzhny in the opening singles match. Nikolay Davydenko of Russia plays Viktor Troicki in the second singles match.

Also this week, the Czech Republic plays Belgium on indoor carpet in Ostrava. Tomas Berdych opens the singles against Kristof Vligen at the CEZ Arena. The series winner faces either Russia or Serbia.

Other best-of-five match series have Argentina facing Britain, Sweden plays Israel, Romania takes on France, Germany faces South Korea and Peru plays Spain. The winners this week will meet in the Davis Cup quarterfinals in April. The Davis Cup final is in November.

Some information for this report was provided by AFP, AP and Reuters.