The former Liverpool, England and Villa forward, currently in Australia with the Newcastle Jets, played alongside the 21-year old Austrian at Villa Park and expects him to turn into a world-class striker.
"Andi's work ethic is unbelievable. The lad is non-stop running. That's very noticeable. You see it in every second of every game," Heskey striker told Villa's official website.
"Out of all the lads there when I was there, of the young lads, he was the best finisher. He found the net time and time and time again. He was phenomenal.
"He was natural but he also worked hard on the training pitch too. It was 50-50 talent and training. If you add those two qualities together, you've got success.
"He always wants to learn, too. He always listens to the coaches and has a real desire to get better and better with his game. That's fantastic to see."