Reports in Russia indicate that Argentina midfielder Ever Banega is fighting a race against time to be fit for the first group stage game against Iceland on June 16.
The Sevilla midfielder trained alone on Monday in the teams first training in Moscow.
Injury had already struck Argentina on the eve of their departure for the tournament, with West Ham midfielder Manuel Lanzini ruled out with a serious knee injury. Enzo Perez was summoned as a replacement for Lanzini.
Argentina’s preparations for this summer’s tournament have been hampered by injuries. Manchester United goalkeeper Sergio Romero was the first to withdraw from the squad in May. Otamendi also withdrew following an injury in training and fans will hope Banega’s injury is not that serious.