Despite Evans being ranked as the world's number 179, Tomic is not expecting an easy encounter against the 23-year-old.
"I was very surprised because I practised with Kei early on in Bradenton and he was playing very, very good in practice," said Tomic. "I thought Kei was going to win that match. It shows you how anyone can play, and all these players that are playing here, they're good.
"You can't take anyone for granted these days, because it proves that a guy that's 150 can play on this day and beat a guy almost top 10.
"But for him to win against Kei was huge. I'm sure if he's playing against Kei way against me it's going to be very difficult for me, that's for sure."
The two meet in the American Grand Slam on Thursday.