"The doctor has told us that Juan Martin has pains in his wrist. He's going to try it out and between tomorrow and the day after we'll decide whether he plays," captain Martin Jaite told a news conference.
"I'm worried, his doctor recommended him to stop (playing) for a fortnight but he wants to play," Jaite added after his team's practice which Del Potro missed.
Argentina are already without injured David Nalbandian, a veteran of three finals, for the tie at Parque Roca on the outskirts of Buenos Aires from Friday to Sunday.
Juan Monaco, Carlos Berlocq and Eduardo Schwank are the other members of the team chosen by Jaite, who is lining up Leonardo Mayer, beaten by Del Potro in the third round of the U.S. Open, as a replacement.
World number 11 Monaco would be Argentina's number one singles player in the event of a forfeit by Del Potro, who had surgery on his right wrist in 2010 a few months after winning the US Open in 2009.