Left-back expects the England international to enjoy a good reception when he returns to Villa Park for the first time since signing with the Red Devils in the summer
The Manchester United winger will return to Villa Park for the first time since he completed a switch worth around £16 million to the Premier League champions in the summer.
Warnock added that he expected Young to receive a good reception from the home crowd.
"I think Ashley will go down as a modern day great for Villa," he told the Daily Mail.
"I wouldn't expect anything less than a good reception for Ashley from our fans.
"He was a great servant to the club but it's not often the Premier League champions and Champions League runners-up want to sign you."
The full-back added that he thought Young would grow into a world-class player given the opportunity to compete in the Champions League.
"We're a club who want to progress but Manchester United are at the top and Ashley has aspirations to be a top, top player," he said.
"He has the ability to be one of the best in Europe and I don't think fans can begrudge him that.