Federer defeated 104th-ranked Andreas Beck and the windy conditions in Flushing Meadows in 1 hour, 41 minutes with the help of 15 aces. Beck kept battling but the world number two proved too strong.
"It's the perfect start, sure. I played Monday, Aug 30, had two days off. I had another easy one physically and here I am in the third round feeling like I'm completely in the tournament," said Federer.
"Obviously they weren't the most difficult matches. I didn't have to save multiple break points or whatever. Even though I got broken today, I feel really good. Tougher matches will only be coming up now, I guess. I underestimate nobody," he added.
The 29-year-old Swiss has now racked up 42 wins in his past 43 matches at Flushing Meadows, and with Andy Roddick and Lleyton Hewitt both out, he is the only previous winner of the US Open left in the men's field.