Argentina coach Alejandro Sabella
Argentina's coach Alejandro Sabella gestures during the 2014 World Cup Group F soccer match against Bosnia and Herzegovina at the Maracana stadium in Rio de JaneiroReuters

Argentina head coach Alejandro Sabella insists that his side needs to improve in their next World Cup fixture, following their narrow 2-1 win over Bosnia-Herzegovina in their opening game of the tournament.

Argentina took the lead in the second minute of the game through an own goal from defender Sead Kolasinac before Messi doubled his side's lead in the second half.

However, the two time World Cup winners looked a bit nervous after Vedad Ibisevic pulled a goal back in the 84th minute. Although Argentina managed to hold on to their lead, Sabella admits that his side need to be better in the next couple of fixtures.

"They were two different halves. In the first one I think we controlled the Bosnians well, but beyond that, we didn't create the kind of depth that we managed in the second half. Obviously we need to improve. It is true that we failed in parts, in part because of my own mistakes," said Sabella.

Nevertheless Sabella acknowledged the impact of star striker Lionel Messi in the second half.

Messi was clearly not on the top of his game in the first half as he failed to trouble the Bosnian defence or create any chances.

However after Sabella brought in Fernando Gago and Gonzalo Higuain in place of Hugo Campagnaro and Maxi Rodriguez after the break, there was a significant improvement in the 26-year-old's game as he went on to score Argentina's second goal.

And Sabella revealed that the half time changes were made to help Messi get back in the game.

"As soon as we brought in Higuain [Messi and Aguero] had more company and we were able to put together the game that has characterised Argentina for a long time," added Sabella. "We brought in two things: Better provisioning and once Messi received the ball, better follow-up and better support."

"Messi is the best player in the world. It is not that he needs a lot. Beyond that there's always a context and it can empower him a bit more. In this case the support - he received a push from his colleagues which empowered him."

Meanwhile, Sabella played down the injury concerns of striker Sergio Aguero, who appeared to be in some discomfort as he limped off the pitch in the 87th minute.

"I saw he was tired. There was very little time to play and I wanted to make the substitution before that when it was 2-0. We needed a fresh player and I was between introducing another attacking player or a defensive one, but I took him out because he was tired," added Sabella.