SURPRISE, Ariz.(AP) Teenager Melanie Oudin has been chosen as the No. 2 player for the United States in the first round of its Fed Cup competition against Argentina this weekend.

Captain Mary Joe Fernandez picked the 17-year-old from Marietta, Ga., over USTA pro tour veteran Julie Ditty in the draw announced on Friday.

I'm really excited. I definitely didn't expect it,'' Oudin said.I've been working really hard.''

Oudin will make her Fed Cup debut against the No. 1 Argentine player, Gisela Dulko, in the second match Saturday. The top U.S. player, Jill Craybas, plays Betina Jozami in the opening match in the best-of-five competition on the hard court surface at the Surprise Tennis and Racquet Club in suburban Phoenix.

Weather could be a problem. The teams practiced this week in sunshine and temperatures in the mid to upper 70s, but the forecast was for a drop to the low 60s on Saturday and upper 50s on Sunday. There is a 60 percent chance of rain on Saturday and 50 percent on Sunday.

Oudin turned professional after reaching the semifinals of last year's U.S. Open junior championships. She made it to the quarterfinals of the Bell Challenge WTA event last October.

Fernandez joked that ``Melanie has been here one more day, so that's why she got the nod.''

But they're both ready to play. It really wasn't a huge difference,'' Fernandez said.They're both first-timers. We're going to see how everything goes tomorrow. We can always make switches for Sunday.''

Ditty was chosen for the U.S. team on Tuesday when Bethanie Mattek withdrew because of a nagging hip injury.

Serena and Venus Williams were invited to be on the team but the sisters declined, citing scheduling difficulties. That left Craybas, 75th in the world rankings, as the top player on the U.S. team.

Barring any changes, Oudin will play Jozami and Craybas faces Dulko on Sunday. The competition concludes with a doubles matchup with Ditty and transplanted South African Liezel Huber facing Argentina's Soledad Esperon and Aranza Salut.

Oudin was the only U.S. woman to advance to the Australian Open through the qualifying draw. She lost in the first round to Akgul Amanmuradova of Uzbekistan.

Dulko is the highest-ranked player in the field at 44th. She has three WTA singles titles, the most recent in Fez, Morocco last May. Dulko has played in 16 Fed Cup events with a record of 12-7 in singles and 4-3 in doubles.

Argentina captain Ricardo Rivera said the matchup will be decided by whichever team is less nervous. Jitters can be overcome by practice, he said.

We practiced between four to five hours a day,'' Rivera said.We practice a lot, and we try to do the things right.''

Fernandez, who played in six Fed Cups, knows that nerves will play a role.

Anytime you're playing for your country, there's tons of pressure,'' Fernandez said.I can't remember one tie where I didn't feel nervous or feel the pressure. You know, you're not just playing for yourself, you're playing for your teammates, you're playing for your country.''

Craybas said she and her teammates should appreciate the opportunity.

Like Billie Jean King wrote in her book `Pressure is a Privilege,' I think when we focus on that, you can overcome anything,'' Craybas said.So we're just going to go out there and fight our hardest. I think realizing that playing for the United States is a really exciting thing to do instead of, you know, trying to worry about it a little bit.''

The United States has 17 Fed Cup titles but none since 2000. Last year's team lost to eventual champion Russia 3-2 in the semifinals. Argentina has never won the Fed Cup. It reached the semifinals in 1986 and 1993.

The winner of this weekend's competition advances to the semifinals against the winner of the Czech Republic-Spain matchup being played in Brno, Czech Republic.