Nash acts as a sporting advisor to Mallorca owner Robert Sarver and will be at the Nou Camp today.
"It is a dream come true for our players and the team," Nash said at an event held at the NBA Café in Barcelona.
"He is the best player to have ever played football and, on top of that, he plays for an impressive team," he stated.
The Canadian is expecting a tough game for Mallorca at the Camp Nou.
"We are in a very nice place, but it will be difficult to stop them," Nash admitted.
"We will suffer. It will be an amazing experience for everyone, but we understand the kind of team that we will come up against."