Dunedin - Argentina star Felipe Contepomi was left fearing the worst after the Pumas failed to turn possession into points during their 13-9 opening World Cup defeat by England.
The Pumas repeatedly overpowered England, bidding for a third successive World Cup final appearance, up front and ran them ragged behind the scrum as well at the Otago Stadium here on Saturday.
But in a match where both sides struggled to land goalkicks under a permanent roof, England replacement scrum-half Ben Youngs struck the decisive blow with the only try of the match 13 minutes from time.
Argentina finished third at the 2007 World Cup, where they made a blistering start with victory in their opening match over then hosts France.
But fly-half Contepomi knew this defeat had left the Pumas on the backfoot in a Pool B also featuring a Scotland side who have always previously qualified for the World Cup quarter-final and who snuck past Romania earlier Saturday.
"In terms of the result, it can cost us dear," said Contepomi, who had to leave the field injured midway through the first half.
"It's always easier if you start by winning your first game in a World Cup.
"But in terms of performance, the whole team has made a big step forward and we can build on this.
"We have three games ahead of us when, hopefully, we can improve."
Contepomi, a qualified doctor, said it was too soon to diagnose the exact nature of his injury. "I don't know, I'm going for an X-ray. It's a cartilage or rib."
Argentina also saw centre Gonzalo Tiesi hobble off with what could be a medial ligament injury.
The Pumas' performance was all the more creditable as the lead-up to this match had seen them play just one Test in nearly a year, a 28-13 defeat by Wales in Cardiff last month.
"Only one Tests in 11 months, we knew it was going to be hard," Contepomi said.
Argentina coach Santiago Phelan added: "We didn't score the points when we got into good positions. The team did what we were planning, we wanted a strong defence and that happened."
The Pumas squandered a possible 18 points through six missed penalties but Phelan refused to blame full-back Martin Rodriguez, who did the bulk of Argentina's goalkicking for the defeat.
"Kicking is part of the game but you can score through other opportunities."