* World number two Federer unavailable to face Czech holders
* Del Potro, Ferrer absent for Argentina and Spain (Adds Corretja quotes)
LONDON Jan 22 (Reuters) - Davis Cup champions the Czech Republic will not have to worry about facing Roger Federer in the opening round of their defence after he was left out of Switzerland's team for the Geneva tie.
The 17-times grand slam champion, still contesting the Australian Open where he will face Jo-Wilfried Tsonga in the last eight on Wednesday, played twice for his country last year but has decided to sit it out the Czech clash.
Tomas Berdych will spearhead the Czech challenge in the tie taking place from Feb. 1-3.
Other notable absentees from first-round action are Juan Martin del Potro, who was not named in Argentina's team to play Germany in Buenos Aires, and Australian Open semi-finalist David Ferrer, who is not in Spain's squad to play in Canada.
Former U.S. Open champion Del Potro said last month that he would not be playing Davis Cup this year.
"The decision was not easy - but I have important goals on the circuit," the injury-prone Del Potro said.
In the absence of Ferrer and Rafa Nadal, who has yet to return to competitive action after a long-term knee injury, Nicolas Almagro will shoulder the main singles responsibility for the top-seeded Spaniards.
Feliciano Lopez returns to the team as the number two singles player, with Marcel Granollers and Marc Lopez, who are through to the Australian Open last four, playing the doubles.
"We are starting a new year in the Davis Cup with the excitement you get from playing for Spain in the top international competition," Spain captain Alex Corretja told a news conference.
"We know it's a very tough tie but I have every confidence in this team and their commitment to provide yet more satisfaction for the Spanish fans," he added.
World number one Novak Djokovic was named in Serbia's squad to face Belgium in Charleroi, although his participation may depend on how much his bid for a third consecutive Australian Open title takes out of him. (Reporting by Martyn Herman and Iain Rogers, editing by Ed Osmond)