The Chilean is hoping to wrap up the Liga title soon but admits that the Argentine star provides his whole team with a boost when he playsAlexis Sanchez has admitted that Lionel Messi's presence on the pitch motivates the rest of his Barcelona team-mates.
The Argentine rose from the bench to score twice in a 4-2 win over Betis on Sunday to move Tito Vilanova's side within just one win of the Liga title.
And the Chilean says he does not know why the 25-year-old was a substitute against the Andalusians but insists he is just focusing on wrapping up the championship.
"What we want most is to be league champions and will go game by game," the 24-year-old told Canal+.
"When Messi plays he contributes a lot to our game, he motivates the team. I don't know why he was a substitute [against Betis].
"The team is calm. If anyone comes in they will be welcome. It is always necessary to do the best things for the team. I have a contract until 2016."
Barcelona' next Liga game is a trip to Madrid to face Atletico on May 12.