Felipe Contepomi will start at inside centre for Argentina in their crunch World Cup Pool B match against Scotland on Sunday despite still suffering pain from a rib injury.
The Pumas' captain suffered the injury in his team's opening 13-9 loss to England and then missed the 43-8 victory over Romania.
But in a huge confidence booster for Los Pumas, the talismanic Contepomi is back for a match that will likely decide the runners-up from Pool B.
Contepomi insisted he was ready to play in a team that mirrored the one selected by coach Santiago Phelan for the England game with the exception of centre Gonazalo Tiesi, who has been ruled out of the tournament with an injury.
"I had a full-on training session today," said Contepomi, holding a bag of ice to his ribs. "This was the day to train myself, have full contact.
"I'm still in a bit of pain, I'm not pain free but it worked well, and hopefully I'll be playing if nothing happens in the next 48 hours."
Contepomi, himself a doctor, was "taking pain killer and anti-inflammatories" and even had "small injections of dextrose" to help heal his injury.
"I knew it was going to be very tight and I'm lucky it healed quickly."
Contepomi said he did not mind shifting from fly-half to inside centre, a position in which he last played in November 2008 against Italy.
"Me playing centre was the best option for the team," he said.
"We don't have many chances to play for the national team, so every chance you get you want to play.
"I'm lucky, it's my fourth world Cup. If I can play as many games as possible, I can," said the Argentinian who will be playing his 15th World Cup match, a new record for an Argentine back - the Scotland game will be hooker Mario Ledesma's 16th World Cup match.
Coach Phelan said that results against Scotland in recent years would count little come Sunday's match.
Scotland notched up a first ever southern hemisphere Test series win with two victories on Argentinian soil last year, before Los Pumas roared back for a win in Murrayfield.
"Argentina are well prepared, we have had two-and-a-half months preparing together and that's the difference from over last three or four years," Phelan said.
"We know Scotland are also well prepared, and playing good rugby. It will be a tough game."
Argentina: 15 Martin Rodriguez, 14 Gonzalo Camacho, 13 Marcelo Bosch, 12 Felipe Contepomi (captain), 11 Horacio Agulla, 10 Santiago Fernandez, 9 Nicolas Vergallo, 8 Juan Martin Fernandez Lobbe, 7 Juan Manuel Leguizamon, 6 Julio Farias Cabello, 5 Patricio Albacete, 4 Manuel Carizza, 3 Juan Figallo, 2 Mario Ledesma, 1 Rodrigo Roncero.
Replacements: 16 Agustín Creevy, 17 Martin Scelzo, 18 Mariano Galarza, 19 Genaro Fessia, 20 Alfredo Lalanne, 21 Lucas Gonzalez Amorosino, 22 Juan Jose Imhoff.
Date: Sunday, September 25
Venue: Wellington Regional Stadium, Wellington
Kick-off: 20.30 (07.30 GMT)
Referee: Wayne Barnes (England)
Assistant referees: Nigel Owens (Wales), Chris Pollock (New Zealand)
TMO: Shaun Veldsman (South Africa)
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