Vardy will break Ruud van Nistelrooy's record of scoring in 10 straight Premier League matches if he finds the net at the King Power Stadium.
If his performance against United last year is anything to go by, he will have little trouble rewriting the history books.
The 28-year-old scored one and had a hand in the other four goals in Leicester's 5-3 win over Van Gaal's team 14 months ago.
United's defence has improved greatly since then, but Van Gaal is aware of the threat Vardy will pose to his team.
Van Gaal described Vardy as a "nasty" and "great" player who he also likened to former Arsenal and Ajax great Dennis Bergkamp.
"He was last season a very nasty player for us," the United manager said.
"He scored, won a penalty, and now he is scoring 10 games in a row, then you are a great player.
"I only know Dennis Bergkamp as a player who did the same with Ajax. It's not so easy to do that."
When asked whether he would consider signing Vardy, Van Gaal gave a terse reply, saying: "That is not your business, I think."