The Barcelona attacker scored what proved to be the decisive goal in La Celeste's 2-1 victory over Bosnia & Herzegovina, with Alejandro Sabella changing his tactics at halftime
Alejandro Sabella started with a 5-3-2 formation and saw his side take the lead in the early exchanges when Sead Kolasinac scored an own goal, but it struggled for the rest of the half and a tactical switch was made at the break.
La Celeste performed better in the second half and Messi picked up his second World Cup goal before Vedad Ibisevic pulled one back, and the Barcelona man was realistic about the performance.
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"Bosnia are a good team and we have things to improve, but the important thing is to start with three points," he told reporters. "In the first half we were too deep and that hampered us in attack.
"The second goal was a relief for everybody and ensured the three points, it was special for me because of the game that I had.
Thousands of Argentina fans filled the Maracana stadium in Rio de Janeiro for the match, and greeted Messi with loud cheers when he walked out on the pitch.
The No. 10 says had no doubts about his country's support, and insists he is focusing on winning the trophy back in the same stadium on July 13.
"The Maracana was great, I had no doubt it would be like that, we keep working towards the dream."