The 38-year-old five-time champion has not won this hard-court Grand Slam event since 2008, but reached the final in 2015 and is on the shortlist of title favourites once again this year.
"We were saying on the practice court two days ago that this is probably the best I've felt in years coming into the US Open again, which is encouraging," the world No. 3 said at a press conference three days before the start of main-draw action, Efe news reported.
"I'm not putting extra pressure on myself. I know it's going to be tough," he said, recalling that he was dealing with back issues in 2017 and did not play the tournament because of injury in 2016.
Federer won five consecutive US Opens from 2004 to 2008 and was on the verge of winning a sixth straight title in 2009, when he squandered a lead and ended up losing in five sets in that year's final to Argentina's Juan Martin del Potro.
He acknowledged on Friday, however, that those days of absolute dominance are behind him.
"I'm not coming in as the overwhelming favourite like maybe I did back in 2006 or 2007. I'm very much aware of how I need to approach this tournament mentally."
Besides the Del Potro loss, Federer has had his share of other disappointments at Flushing Meadows over the past decade, having twice lost to Serbia's Novak Djokovic - in the 2010 and 2011 semi-finals, after holding a pair of match points.
Federer also lost to Djokovic in a close four-set match in the 2015 final, a year in which the Swiss was in sublime form and did not lose a set until the final Sunday.
The Swiss suffered an even more painful loss to the Serbian star a few weeks ago in the Wimbledon final, when he squandered two championship points on his own serve before falling in a fifth-set tiebreaker.
Federer had defeated Spanish great Rafael Nadal in the semifinals and thus was one point away from beating both of his arch-rivals in the same Grand Slam tournament for the first time in his career.
To win an Open Era-record sixth US Open title, he might have to run that gauntlet once again, although at this year's Flushing Meadows Federer could face Djokovic in the semifinals and Nadal in the final.
A Federer-Nadal match at the US Open would be a first for those two all-time greats, who are in first and second place in all-time Grand Slam singles titles with 20 and 18, respectively.