Argentina made an explosive start, with Angel Di Maria producing a great save from Mexico goalkeeper Alfonso Blanco early on as his powerful volley was tipped over the top. However, Carlos Vela also came desperately close to opening the scoring at the other end when he had a great opening but Argentina's Sergio Romero got enough of a block on it to turn the ball away for a corner when the shot passed between the keeper's legs.
Vela then hit the post after half an hour with a shot on the turn but Maximiliano Moralez got Argentina's winner just before the break with a drive which deflected in off Julio Cesar Dominguez. The Mexicans tried to get back into it but Argentina rarely looked troubled after the break and their lead stayed intact.
Many people fancied Mexico for the title following their victory at the FIFA U-17 World Cup in Peru two years ago, but they are now heading for home, while Argentina remain on course for a sixth U-20 title and they meet Chile in Toronto on 19 July for a place in the final.