Spain's two most historic clubs go head to head at the Nou Camp tonight, with the Catalan side eight points in front of their rivals.
"[Mourinho] is a good coach who does his job," the Argentine told todo-barcelona.net. "So is Cristiano Ronaldo, [who is] a great player."
Tito Vilanova has steered Barca to the top of La Liga, winning all six of his games in charge.
Messi said that there has not been much change under the new boss, who took the reins from Pep Guardiola at the end of last season.
"[With Tito], you will see the same Barcelona from past seasons," he added. "Our style of play will not change because Tito thinks like Pep in this regard. There is no change.
"Pep left a mark on the history of football. He gave me the bonus of playing in different positions on the field and that's something he did with the team.
"He changed and reinforced the philosophy of playing good football, but with the perfect balance in defence and attack."
Messi has already struck six goals in Barca's six La Liga games so far this season.