A year on and the Swiss is back on top of the world rankings, the Wimbledon champion and chomping at the bit for a sixth title at Flushing Meadows.
"I felt good last year but probably felt that at times the matches were not always on my racquet," Federer said on Saturday.
"This time around I feel like if I'm playing well I can dictate who's going to win or lose. It's going to take something special from my opponent to win."
"That's how it feels right now; then again, I might walk away from Monday having lost in the first round."
In each of the past two years, Federer has lost to Novak Djokovic in the semi-finals, failing to convert two match points on each occasion.
The Swiss said tough losses at the French Open and Wimbledon may have knocked his usually supreme confidence.
"Maybe I did come into the U. S. Open with a few losses that already maybe shook me up a little bit," he said.
"But I knew at the U. S. Open I usually play so, so well, and then everything went great.
"I had a great campaign into the semis and two sets to love up, match points as well. It was just not meant to be."
His victory over Andy Murray at Wimbledon last month gave him a record 17th Grand Slam title.
Murray gained a measure of revenge by beating him to win the Olympic title but having regained the number one ranking from Djokovic, Federer believes he is in the form to win again.
"If you look back at the results I had the last, let's say two years, I was actually extremely close on many occasions to give myself chances to win Slams.
"I'm just happy how I'm playing. I already reached my goal for the year becoming world number one, getting Wimbledon again and getting a medal for Switzerland. It's been incredible.
"But I do have this one left for me this year where I really, really want to do well and I couldn't be more happy returning here as number one. It's super exciting."
With his 31st birthday behind him, Federer knows that every missed opportunity is seen as a sign that his best years are gone.
But Federer said he was used to seeing both the highs and the lows in more perspective.
"Right now I know obviously people think I can win every Grand Slam that comes up and if I don't win the US Open, I will never win one again. It's always the same story.
"I'm just happy I was able to get Wimbledon. It just shows what I knew; that if I do play well I can win Grand Slams."