The Barcelona superstar tormented Paraguay mercilessly as the favourites produced their best display of the tournament and advanced to a showdown with Chile in Saturday’s final.
Although Messi failed to end his run of more than 900 minutes without an international goal from open play, he turned creator as Argentina tore Paraguay apart.
Goals from Angel Di Maria (2), Marcos Rojo, Javier Pastore, Sergio Aguero and Gonzalo Higuain completed an emphatic rout for the South American giants.
A satisfied Messi was delighted Argentina’s potent collection of attacking talent finally appears to have clicked with Saturday’s final looming.
“We’ve been playing well – we knew once we scored one goal, many more would come, and that’s what happened,” said Messi as he collected his man-of-the-match award.
“We got an early goal and then found more space, and then we got the second. We continued to play the same way and more goals came.”
Argentina, who finished runners-up in last year’s World Cup, are determined to clinch a first major title in 22 years at the Copa America.
“The important thing is that we’ve achieved our first objective by reaching the final. Now we need to win it,” Messi said.
Manchester United defender Rojo and Paris Saint-Germain’s Pastore had given Argentina a 2-0 lead midway through the first half before Paraguay pulled one back through Lucas Barrios.
But any Paraguayan hopes of repeating their heroics in the group phase – when they came back from two goals down to draw 2-2 – were snuffed out by two goals in six minutes from Di Maria early in the second half.