The Canadian has conceded that he must raise his game if he is to progress any further at Flushing Meadows.
"I'm just happy with the outcome and that I managed to sort of make the most of that moment and just find a way to win," Raonic told reporters. "Everything else I've gotta hope gets better in the next round. I don't think I struggled with my serve that much in a long, long time.
"A lot of double faults, and it wasn't just one double fault per game. When I double faulted, I double faulted consistently a couple times in a row, so that made my job a lot more difficult and it gave him a little bit more freedom at the same time."
Raonic had never won in the main draw in New York prior to today.