While he is pleased with his win over Nishikori, Evans is adamant that he has not yet reached his ambitions at the American Grand Slam.
"I'm happy with how the day went and how the match went, but I really want to win the second round," Evans told reporters.
"One round isn't enough at the minute, so I want to win again on Thursday.
"I've played some good matches for the last five weeks. I really want to go far in the tournament, win a few more matches, and I'm ready to play again."
Evans and Tomic meet in the second round on Thursday.