BUENOS AIRES — Former US Open champion Juan Martin del Potro will ignore medical advice to rest his injured left wrist and open against Radek Stepanek Friday in the Davis Cup semifinal between Argentina and the Czech Republic. Argentina lost last year's Davis Cup decider to Spain for a record fourth defeat in finals, providing del Potro with all the motivation he needs to play. “I'll try to give as much as I can despite the fact the doctor has told me not to play,” said the right-handed del Potro, whose last match was a loss to Novak Djokovic in the quarterfinals of the US Open last week. “This is a chance to play in front of family and friends and people close to me who can never see me play. “If this were not a semifinal perhaps I would have thought more about it.” The evaluation of Argentina team doctor Miguel Khoury was clear. “This is an act of courage by Martin, due to the risk he is taking by playing with this injury,” Khoury said. The second singles match Friday will pit Argentina's Juan Monaco against Tomas Berdych on clay at a sold-out Parque Roca on the outskirts of the Argentine capital. Berdych lost to eventual champion Andy Murray in the US Open semifinals. “Berdych is a player who comes here with lots of confidence,” Monaco said. “But he's not Andy (Murray), he's not (Roger) Federer.” The doubles on Saturday will be Argentina pair Carlos Berloc q and Eduardo Schwank up against Ivo Minar and Lukas Rosol. The reverse singles are Sunday. The Czechs have won three of four head-to-head matches against Argentina in the Davis Cup. In the two most recent, the Czechs defeated Argentina in the 2009 quarterfinals in Ostrava, Czech Republic. Argentina won in 2005 in a first-round match in Buenos Aires. The Czechs won the Davis Cup in 1980 playing as Czechoslovakia. Querrey vs. Ferrer Sam Querrey will launch the US fight to upset holder Spain on their home red clay in the opening Davis Cup semifinal duel against world No. 5 David Ferrer in Gijon Friday. Querrey's giant-slaying teammate John Isner faces Nicolas Almagro in the second rubber of the tie as five-time champions Spain, nicknamed the “Armada”, aim to reach their second Davis final in a row. On Saturday the six-foot-plus American twins Bob and Mike Bryan, the top-ranked doubles players in the world, face Marcel Granollers and Marc Lopez, before the return singles ties on Sunday, according to the draw made in Gijon, northern Spain, Thursday. Spain has dominated the Davis Cup over the past decade, winning it five times, and are surfing a wave of 23 consecutive victories on home soil. But it will have to do without its injured star Rafael Nadal, who continues to rest his troublesome knees on the sidelines. US team captain Jim Courier has called the trip to Spain the toughest mission in the Davis Cup but his team is hopeful of an upset having won its last four straight clay-court ties. The Americans have lost their last two Davis Cup ties against Spain and they are without the newly-retired Andy Roddick, who has been his country's mainstay in the competition over the last decade. But, under the captaincy of former Grand Slam winner Courier, they have chalked up back-to-back away wins in Switzerland (5-0), where Isner shocked Roger Federer, and France (3-2), where he defeated Jo-Wilfried Tsonga. — Agencies