Canada are preparing for a colossal Copa America semi-final showdown against Argentina on Tuesday in what their coach Jesse Marsch has likened to a David verses Goliath battle.

Argentina, World Cup winners in 2022, are defending Copa champions and top the FIFA rankings, while Canada are ranked 48th in the world and are making their debut in the tournament.

"They've only lost twice in five years," Marsch said of Argentina."(Lionel) Messi is the best player to ever play the game. But we believe we have a chance and that's the way we're preparing."

Despite losing 2-0 to Argentina in their opening match on June 20, in which Messi set up both goals for Julian Alvarez and Lautaro Martinez, Canada remain confident having advanced to the semi-finals following a penalty shootout win against Venezuela.

"We know how good Argentina is because we played against them but we also had success in certain moments," Marsch told reporters. "I said after the (Venezuela) match that we probably have to play a perfect match and maybe even then it may not be enough."

While Canada had learned a lot about Argentina from the opening group match Marsch said Messi's side would probably move up a gear in the semifinals.

Messi was on the pitch for the whole of Argentina's quarter-final shootout win over Ecuador despite dealing with a muscle injury during the group stage.

"He's doing OK and he's going to be part of the match," Argentina coach Lionel Scaloni told reporters. "It's up to me to decide and when I see he's in good condition, even if he's not 100% he will still play... Even when he's not at his best, he still has a lot to give."

The winner will move on to the final in Miami Gardens, Florida, on Sunday, meeting either Uruguay or Colombia, who play their semi on Wednesday in Charlotte, North Carolina.