Juan Martin Hernandez admits the loss of Marcelo Bosch is a big blow for Argentina ahead of their Rugby World Cup quarter-final against Ireland.
The Pumas centre was suspended for one game for a tip tackle on Theuns Kotzè in last Sunday's win over Namibia, and will therefore miss the clash at the Millennium Stadium.
Hernandez, who would have partnered Bosch in midfield, has called on his replacement, potentially Jeronimo de la Fuente, to be decisive, particularly in defence.
"'Chelo' is a great leader in defence, in our backline at least. He can read oncoming attacks better than any of us," explained Hernandez.
"Sometimes, it’s very hard for a defending outside centre or wing to make the right calls, but he always gets it right.
"That is why his replacement, though more inexperienced, must be as effective as him and capable of making the right decisions."
Bosch isn't the only player missing from the game, with Sean O'Brien also picking up a one-week ban for striking Pascal Papé last week.
With Paul O'Connell and Peter O'Mahony also out of the tournament through injury, Hernandez is optimistic that the Pumas can get on top in the crucial battle at the breakdown.
"Nowadays, the key to every game is at the breakdown and in the resulting rucks. Whoever wins that battle will control the breakdown and therefore keep the ball."
"I truly hope so (Ireland's losses will influence the game), but they have quite a good bench. I personally know O’Brien and he’s excellent at the breakdown. I hope his absence will benefit us.
"I think we should focus more on our game and the change in our style that has been working so far. We need to be strong."