Argentina, trying to reach its first Davis Cup final since 1981, got a victory by David Nalbandian over Dominik Hrbaty on Friday to even its semifinal series with Slovakia at 1-1 on the first day of the best-of-five series.
The other semifinal between Croatia and Russia also was tied 1-1.
Argentina is playing in its third semifinal in four years. Slovakia reached the semifinals for the first time after beating last year's champion, Spain, and the Netherlands. Russia is the only semifinalist to have won the Davis Cup.
At Bratislava, Slovakia, Karol Beck sent the home country to an early lead in the hard-court match by defeating eighth-ranked Guillermo Coria 7-5, 6-4, 6-4. Nalbandian tied the series by downing Hrbaty, Slovakia's top player, 3-6, 7-5, 7-5, 6-3.
In Split, Croatia, Russia's Nikolay Davydenko beat Mario Ancic 7-5, 6-4, 5-7, 6-4. Ivan Ljubicic, who plays his best tennis in Davis Cup, rallied to tie it with a 3-6, 6-3, 6-4, 4-6, 6-4 win over Mikhail Youzhny.
"It was probably the best indoor match I have ever played," Davydenko said.
Russian captain Shamil Tarpischev led the women to the Fed Cup title last weekend, and is trying to become the first person to sweep Davis Cup and Fed Cup titles in the same year.
In Saturday's doubles, Slovakia's Beck and Michal Mertinak will face Argentina's Nalbandian and Mariano Puerta, while Ljubicic and Ancic play for Croatia against Russians Youzhny and Dmitry Tursunov.
In the playoffs, the winner remains in the elite 16-nation World Group and the loser drops to zonal play next year. That competition is featuring the world's top three players - No. 1 Roger Federer, No. 2 Rafael Nadal and No. 3 Andy Roddick.
The United States, in danger of being relegated from the World Group for the first time in 17 years, got an important win from Roddick against Belgium. He defeated Christophe Rochus 6-1, 6-2, 6-3 after James Blake lost to Christophe's brother, Olivier Rochus, 6-4, 7-5, 6-1.
"I controlled the beginning of each set and that was pretty much it," Roddick said.
Federer, the Wimbledon and U.S. Open champ, routed Britain's Alan Mackin 6-0, 6-0, 6-2 to give Switzerland a 2-0 lead.
"I've been waiting for this moment a long time," said Federer, back with the Swiss team for the first time in 17 months. "I've never gone 6-0, 6-0 on the ATP tour and I don't remember the last time I played someone ranked that low."
Nadal, the French Open champion, beat Italy's Daniele Bracciali 6-3, 6-2, 6-1 after Juan Carlos Ferrero was upset by Andreas Seppi 5-7, 3-6, 6-0, 6-3, 6-2 in Torre del Greco, Italy. Spain, the 2004 champion, and Italy are tied 1-1.
In other World Group playoffs it was: Austria 1, Ecuador 1; Chile 2, Pakistan 0; Czech Republic 1, Germany 0; Sweden 1, India 0; and Canada 1, Belarus 0.