By Simon Evans
"I've been playing well the last couple weeks, and today was just another proof that I'm playing really well," he told reporters.
"It's nice knowing that the hard work already in the off season after Wimbledon paid off right away. I know it's not all (about) work from there but I've been committed to this sport for many years. I think when you do that and give yourself chances over and over again, you'll break through by winning tournaments again.
"I came close a couple times earlier in the season. Should have won Halle, I felt. Could have won Madrid, but things didn't really work my way.
"I was maybe playing a little bit too passive. Now I'm taking it more to the opponents again. I'm happy that that's the right game plan right now," he added.
Fish enhanced his growing reputation as a threat on the hard court with a display that bodes well for his chances at Flushing Meadows and his recent run, including wins at Newport and Atlanta, takes him up to 21st in the world.
There was nothing to choose between the pair in a tight opening set which Fish won on a tiebreak but the momentum shifted in the second set when Federer, facing defeat, raised his game a notch to run out a 7-1 winner in another tiebreak.
Fish maintained his focus on continued to serve and return well but Federer produced the first break of the match to go 5-4 up and then kept serve to win.
Andre Agassi, in Miami eight years ago, remains the only American to have beaten Federer in the 15 finals where he has taken on a U.S. player.
The latest triumph came after just three hours and 25 minutes of tennis in the tournament before the final, thanks to a first round bye, a retirement by his second round opponent and a third round walkover.
But it was not fitness that proved the difference Sunday for Federer, wearing his pink shirt for the final time.
"He's a true champion, the greatest of all time," said Fish on court.
While there has been much talk of Federer being in decline, his confidence would indicate he has plenty left to give yet.
"I thought today was just a really close match that went my way. I had huge belief that I was going to win today from the first point until the end. That sometimes can make a bit of a difference," said the world number two.
"I was positive all the way through because I felt I was playing well, even though I lost the first set. So I never got down on myself and doubted myself. I think that reflected in the game."