The 28-year-old told FIFA.com: "I was lucky enough to make my debut and to do so in such an important match, and at such a tough time for anyone to come on was incredible.
"I feel so happy inside, though obviously I'm sorry that Di Maria picked up an injury. Let's hope it's nothing serious.
"It's a dream come true. It's been such a long time since we last reached the semis at the World Cup. This team has fought really, really hard to get this far and I'm proud to be part of such an incredible group of players, even if I haven't played that much up to now."
Argentina will face the Netherlands for a place in the final next week.