The premier international team event in men's tennis is set to start on Friday, as defending champion Spain hosts the United States in the semi-finals of the Davis Cup in Gijon.

Both teams are missing big name players, with Spain playing without superstar Rafael Nadal, who is nursing a knee injury. The U.S. is playing without Davis Cup-stalwart Andy Roddick after he retired at the U.S. Open.

Roddick was stellar in his career in Davis Cup matches, going 33-12 and playing on the team that won the championship in 2007.

Spain is the defending champions after beating Argentina last year and hasn't lost at home or on a clay surface in over 10 years. The team has won three of the last four Cups and previously beat the U.S in both 2000 and 2004.

"Spain is the favorite. They could make three or four Davis Cup teams with how many players they have. (But) we'll take our chances," U.S. captain Jim Courier said Thursday to the Associated Press. "The preparation is the same for us, no different. It's all about execution."

The U.S. beat Switzerland and France to advance to the semi-finals, while Spain beat Kazakhstan and Austria.

John Isner leads the American team in Roddick's absence and joins Sam Querry and twins Bob and Mike Bryan.

Isner won all four of his matches this past year, including wins against Roger Federer and Jo-Wilfried Tsonga. He will play Nicolas Almagro for his first match. Isner has a powerful serve and will try to use to his advantage on the slower clay courts.

"Our team has played in some tough environments before and we expect a tough environment tomorrow," said Isner, who earned his four wins against Switzerland and France. "It's going to be a big challenge, but it's not going to be anything I'm not used to."

Querry will open the singles on Friday as he takes on David Ferrer, who made it all the way to the U.S. Open semi-finals last week. The two have previously faced off on a hard court, but have never played on clay against each other.

Nadal is considered to be the best clay court player in the world, but Spain's Almagro and Ferrer have a 21-1 combined record on clay courts. Isner and Querry have gone 6-7, but advanced in their last two matchups against France and Switzerland on clay.

"Nadal's the best clay-court player today, probably the best of all-time. If he was in the lineup, their lineup would be a little stronger," Isner said. "It's going to be tough either way, the team is so deep."

Following their doubles championship at the U.S. Open, the Bryan brothers will take on Marcel Granollers and Marc Lopez, who are playing in their first season together. The Bryans have won a record 12 Grand Slam titles.

"This could be our toughest away tie match," Mike Bryan said. "We'll treat it just like the U.S. Open final a week ago."

The winner will play the Czech Republic or Argentina in the final in November.