Juan Martin Del Potro said he could not have hoped for a better Davis Cup debut after thrashing Nikolay Davydenko.

His straight-sets victory over the world number five put Argentina 2-0 up in the semi-final clash with Russia.

His 6-1 6-4 6-2 victory followed David Nalbandian's 7-6 (7/5) 6-2 6-4 triumph over Igor Andreev earlier in the day and put Argentina firmly in the driving seat for a place in the final against either Spain or the United States.

"I had the best debut in Buenos Aires ever," said 19-year-old Del Potro. "I played consistently, very focused and I had no problems to control my nerves.

"I owe all that to Luli (captain Alberto Mancini), who was in the chair, and the team, who backed me.

"I wasn't worried about my tennis or my shape. I was only worried about taking it calm, with the fans' pressure. I only wanted to give Argentina one point."

In his first Davis Cup home match at the Parque Roca stadium in Buenos Aires, Del Potro made a great start to race into a one-set lead.

He broke the Russian twice at the start of the second set and despite Davydenko clawing it back to 5-4, Del Potro served to seal the set.

The third set was merely a formality as Del Potro again had two early breaks which proved decisive.

Nalbandian was made to work for the first set against Andreev, coming back from 4-1 down in the tie-break, but cruised through the next two sets for a comfortable win.

"The tie-break was the game's most important moment," said Nalbandian. "Being 1-4 was crucial. I won it with fighting spirit and running and also with a bit of luck.

"At 4-2 in the second set I found the way to thwart his serve as until then I had a lot of problems with that.

"It was hard to get into the match. The tie-break was crucial for both. Since then I played the better and everything changed.

"I played solid tennis. I am feeling much better since Wimbledon and I don't feel any pain. It was my best game of the year and the people's support helped me not to give up. I thought that it was going to be longer match but luckily it was easier than I expected and I ended well."

Andreev admitted he found it tough to overcome losing his lead on the first-set tie-break.

"Being 4-1 in a tie-break with two serves ahead is a lot," he said. "(After losing it) I tried to continue playing and doing things correctly, but I couldn't focus anymore. I tried to forget about having lost it, but that is hard and always has an influence.

"Nalbandian's tactic was to find my backhand before I could take the initiative with my forehand. He can play his backhand shot in any direction and that is really good.

"So it was very difficult to change that situation. He played very well and deserved the triumph. I had several chances, but I couldn't find my game."

Argentina captain Mancini confirmed that David Nalbandian and Guillermo Canas will be the doubles pairing in the third and potentially decisive match.

After Nalbandian's straighforward win, Mancini opted for him instead of Agustin Calleri.

Russia captain Shamil Tarpischev would not confirm if Dmitry Tursunov and Igor Kunitsyn will be paired together.