Well the Argentine team consists of:
David Nalbandian
Gaston Gaudio
Juan Ignacio Chela
Lucas Arnold
So are David and Gaston their top 2 singles players for the tie

Or will Chela replace one of them?
Well lets examine their indoors records:
The source for all of my stats is
www.tenniscorner.net which may differ slightly from atptennis and itf depending on which counts DC and which doesn't.
Anyhow, their records indoors are as follows:
David Nalbandian: 1-1
He's only been fulltime for about a year now, which would account for the lack of experience. Both matches were played in 2001 in Moscow. He beat Anthony Dupuis, then lost 4-6 6-7 to Kafelnikov.
So his indoor abilities are a question mark. However as the Wimbledon final, Toronto quarters, and US Open 3rd round from last year (where he beat Escude 7-5 in the fifth, then lost to Kafelnikov in 4) would indicate, he definately does have the ability to play on faster surfaces then some would assume.
Gaston Gaudio: 2-6.
He didnt play his first atp indoor tournament untill 2000 where he went 0-4, with losses against: Prinosil, Golmard, Rafter and Pavel. In 2001 he went 2-2 with wins against Dupuis, and Tabara. His losses were from Clement, and Ljubicic.
I'm not sure what to make of this really. If he possess the ability to do well on indoor courts, he is yet to draw from it.
Chela: 0-0
He has no record of having played indoors on tenniscorner.
Arnold: 0-0
Seeing as he is here as a doubles player his record indoors in singles, is fairly irrelevant.
I did this all to kill time, but it did satisfy my point. Even in poor form, Safin should definately be the fave against Gaudio, and has more experience indoors then both David and Chela.
Though both of the latter two are questionable as we haven't seen enough of them/any of them indoors to make that call.
I think Chela is potentially their toughest challenger, personally.