Alejandro Sabella's side arrive at the tournament among the favourites to go all the way in Brazil and lift the trophy for the first time since 1986.
Hajrovic, however, argues that Safet Susic's men may be in better physical shape than the Albiceleste ahead of the game.
"Physically we are ready," the Galatasaray man told 24sata.info.
"We played great in the preparatory matches against the Ivory Coast and Mexico so we expect to be [great] in Sunday's encounter with Argentina.
"We're doing well and I believe we are at [the level of] and maybe even better than Argentina.
"The normal thing is to have a bit of stage fright because we play the first game ever at the World Cup finals. However, it will be great motivation.
"Everyone expects to play and get a result, supporters say we will and this will get us our place in the second round."