Patricio Albacete says Argentina are well prepared for Scotland's game plan after Andy Robinson included Ruaridh Jackson and Jim Hamilton in his side.
Albacete said of fellow lock Hamilton: "He is a very physical player.
"They have picked a very hard pack and I think they are trying to confront us in there.
"They put Jackson at number 10, so I think they are going to try to find spaces. We have trained well and hope we will be ready to defy Scotland."
Horacio Agullo was looking forward to battling against the "dangerous" Max Evans on the wing but also pinpointed Hamilton as a threat in Sunday's crucial Pool B game.
"He is a big bloke, but I don't know him much," admitted the winger who is back at Hindu Club in his homeland after a spell with Leicester Tigers.
"I know he used to play at Leicester before.
"The boys told me he is a nice guy and hopefully he won't punch me for nothing!"
Despite his jocular mood, Agullo realised the importance of the game against Scotland, a victory for whom would send Robinson's side through to the knock-out stage and end Argentina's hopes unless Romania have caused a surprise against table-topping England the evening before.
"It is the most important game for us," Agullo told BBC Scotland. "We need to win on Sunday."
Scotland have won their last two games against the Pumas, winning in South America last summer when the hosts were missing many of their top European-based players.
Winger Gonzalo Camacho said: "We have played a lot of games with Scotland in the last few years, so we know each other very well I think.
"They are a very good team and have improved a lot since those games and they beat us in the last two games.
"Sunday is our chance for revenge against them and we will try to win. It is a big game for us."
Biarritz centre Marcelo Bosch, who has yet to play against Scotland, agrees it will be a tough game but fully expects his side to come out on top.
"It is our most important game in the last four years, so will take the game as a final and we expect to win, of course," he said.
"We know that throughout the year we are perhaps not together a lot.
"But, in this period of three months, we have been together and trained for this World Cup and worked on our strategy and technique."
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