The Czech Republic took a comfortable 2-0 lead over Argentina Friday in the Davis Cup semifinals on the strength of singles victories by Radek Stepanek and Tomas Berdych.

Stepanek got the defending champion Czechs off to a strong start at the O2 Arena in Prague with a convincing 7-6 (7-3), 6-3, 6-2 win over Juan Monaco.

The 61st-ranked Czech veteran committed numerous unforced errors in the early going but began to control the match after winning the first set in a tiebreaker. His flat forehand and skillful net play heaped the pressure on Monaco, who was unable to keep his opponent pinned back at the baseline.

"If the other guy is better, the sportsman-like thing is to admit it. He beat me fair and square," Monaco said afterward.

"I think he played much better than I did. I had my chances in the first set, but I didn't take them."

"He's a good player here (on the fast hard-court surface) and did a great job," the 30th-ranked Argentine added.

The second match was more competitive, with the 93rd-ranked Lorenzo Mayer surprising the fifth-ranked Tomas Berdych by taking the second set.

In the end, however, Berdych had too much firepower for his opponent, striking 24 winners to the Argentine's 13 over the final two sets for a 6-4, 4-6, 6-3, 6-4 win.

The Czech Republic can advance to the Davis Cup finals by winning Saturday's doubles.

In Friday's other semifinal clash, Serbia, the 2010 Davis Cup champions, and Canada split the opening singles matches at Belgrade Arena.

Just five days after losing the U.S. Open final on a hard court to Rafael Nadal, world No. 1 Novak Djokovic made a smooth transition to indoor clay to rout Vasek Pospisil 6-2, 6-0, 6-4.

But big-serving Milos Raonic drew Canada even with a come-from-behind 5-7, 6-3, 3-6, 6-3, 10-8 victory over Janko Tipsarevic.

Raonic's power was the difference in the four-hour and 11 minute contest, as he fired 34 aces and struck 105 winners.

Spain, meanwhile, put itself on the verge of a spot in next year's World Group by winning the first two singles matches in Madrid over Ukraine.

Fernando Verdasco lost the first set, but came storming back to defeat Alexandr Dolgopolov 3-6, 6-4, 6-4, 6-2 on the red clay at the Caja Magica arena.

Nadal then quickly gave the Spaniards a 2-0 lead by trouncing Sergiy Stakhovsky 6-0, 6-0, 6-4 in the second match.

The world No. 2 will team up in the doubles with Marc Lopez as Spain tries to wrap up the tie on Saturday. EFE