The Atletico Madrid boss, who made 100 appearances for Argentina as a player, says the Barca star stands alone as the game's No.1
Messi scored from the penalty spot as he captained the Albiceleste to a disappointing 2-2 draw in their Copa America opener against Paraguay last week before helping his side to a 1-0 victory over Uruguay which has seen them qualify for the knockout stage.
Argentina face Jamaica in their final group game on Saturday hoping to secure top spot and Simeone believes Messi is the man to lead Argentina to their first major title in 22 years.
"Messi is the No.1; no player today can even come close,” Simeone told Tyc.
“Lionel can hopefully lead to Argentina to win the Copa America and then the World Cup.”
Simeone went on to add that he considers any comparisons beteween Messi and Diego Maradona are futile.
“Comparisons always serve only the controversy, to set one of them aside is not fair," he added.
"Maradona and Messi played in different times and in different positions. Messi is much more a striker, Diego was all over the entire pitch.
“They are two extraordinary players. Messi has won four Champions Leagues… you cannot compare these two great players.”
Atletico Madrid coach Simeone played 106 times for Argentina, lifting the Copa America in 1991 and 1993.
Messi, who is yet to win a title with Argentina at senior level, will make his 100th appearance for his country against Jamaica.