Rodrigo Palacio, Javier Mascherano and Maxi Rodriguez scored in a 3-0 win over Trinidad and Tobago on Wednesday as Argentina continued their preparations for the global showpiece.
Only hosts Brazil are more favoured to win the World Cup and Messi feels his team's serious approach to pre-World Cup friendlies can hold them in good stead.
"Yes, it is just a friendly and we are very close to our trip (to Brazil) but we are going to play with all we have," Messi said.
"No one wants any (injury to) occur, we are all being very careful of that but we still all want to win, do our best, play seriously and I believe we did that.
"I believe we have a very strong team, very unified and more than that we also have really great players."
Mascherano echoed Messi's thoughts and said that coach Alejandro Sabella had drummed into his squad the importance of gaining pre-tournament rhythm.
"Our minds are on the World Cup, but you have to keep playing," he said.
"The team has to function well together… if not we will play poorly in our first game.
"Historically any problems our team have usually surface in the first game and I don't think this happened today. For me that was the most positive thing I took away from today's game."
Argentina play a final friendly against Slovenia on Saturday before opening their World Cup campaign with a Group F clash against Bosnia-Herzegovina on June 15.
