Often criticised for not producing his world-leading Barcelona form for his country, Messi has led the Albiceleste to the final with several key contributions throughout the tournament in Brazil.
Beckham told Adidas Football's YouTube channel that Argentina would beat Germany 3-1 at the Maracana tomorrow, going on to say: "Germany came to the tournament with great experience, people are not too surprised they've got as far as this.
"There's no particular star, they've just a great group that play well together.
"Argentina have a group of talented players who play with a lot of passion, but Lionel, I'm just excited to see him play."
Messi was yesterday named as one of the 10 Golden Ball nominees for the tournament's best player.