The Frenchman, who currently sits at world No 69 but has been ranked as high as No 25, never looked in trouble on his serve but forced five break point opportunities, taking three of them.
Sitak played just three singles matches in 2016 - all first round qualifying ties at Auckland, Chengdu and Metz - so it was going to be a difficult assignment. Sitak had impressed in winning the New Zealand Championships last month, especially in the final against Finn Tearney, but this was a different level.
"I had no expectations at all," admitted Sitak. "I just wanted to play well, have fun and engage the crowd. I don't think I played as well as I could have but he didn't give me a chance to play well."
"He was taking every ball on the rise and all I did out there was run from side to side. I couldn't really do anything to pressure him except for my serve; I think I served really well in the first set."
Sitak has been a doubles specialist over the last few years and is back on court in his preferred discipline on Wednesday night, alongside American Nicholas Monroe against Michael Venus and Robert Lindstedt.
But he is open to more singles in 2017, especially if he is required for Davis Cup duties.
"If they need me for singles I think I can still play good singles," said Sitak. "I'm ready for anything."