Gerardo Martino voiced his concern over Argentina's second-half collapse after the Copa America favourites opened their campaign with a dramatic 2-2 draw against Paraguay.
Argentina looked on track for a routine win at half-time thanks to goals from Sergio Aguero and returning captain Lionel Messi in La Serena on Saturday.
"I think today is clear that our team had two performances, I don't say until the Nelson goal because I guess there was a previous chance, that I think it was the one made us feeling less confident," Martino told reporters.
"But there were 50 or 55 minutes where we managed the game and could score. After that, we had many doubts, we went backward in the field, we couldn't keep the pressure as we did in the first half, and couldn't solve the different tactic of the opponent with two players inside.
"And we lost the composure of the first half."
Martino, who introduced Carlos Tevez, Gonzalo Higuain and Lucas Biglia before Paraguay's equaliser, added: "What worries me most are the two extremes that the team played at.
"It is clear we need to play games with absolute control, even we had some matches were we haven't had too much control we didn't suffer a lot.
"I have the feeling today we lost the control and the opponent had four or five chances, which let them to draw."
"It is true it is a blow, we have to assimilate because were playing a game under control, well played, with two goals ahead, but now the feeling is not the same than when the first half ended," the former Barcelona boss said.
"But I don't believe we have to modify our way of playing, it doesn't have to affect us, we have to keep trying, we are not talking about a quarter-final or semi-final. But we have to amend things from now on, because it is a sin to draw this kind of game given we had it so under control."
