In other words, he remembers what it felt like to go through what his rival, Rafael Nadal, is going through for a second straight year in New York.
After Federer's windblown-but-routine 6-4, 6-3, 6-3 victory over Paul-Henri Mathieu at the U.S. Open on Saturday, attention turned to the bigger picture — Federer, Nadal and their places in tennis history.
Federer finally won the French Open in 2009, making him the sixth man to win all four major titles. Before that, he lost in the final at Roland Garros in 2006, '07 and '08.
Nadal, who has never been to the final at the U.S. Open, won his first Australian Open title in 2009. Now, he needs to win it all at the U.S. Open to cap his career Grand Slam.
"I guess it's somewhat similar," Federer said. "I won the other three Grand Slams rather quickly, as well, like he did."
Federer needs three more wins to reach his seventh straight U.S. Open final. Nadal has lost in the semifinals in his last two trips to Flushing Meadows. His third-round match this year is set for Sunday against former top-10 player Gilles Simon.
Federer owns a record 16 major victories, while Nadal has eight. Nadal is five years younger, so he has time, but in Federer's opinion, he'll almost certainly need at least one championship in New York if he's ever going to be in the conversation about the greatest tennis players ever.
"Clearly, he has a chance because he's young enough," Federer said. "Obviously, I guess he would need to win the U.S. Open to put himself there. He's won the Olympics, done some amazing things. So, he'll have a shot at it, I'm sure."
Nadal, who defeated Denis Istomin in a tense, three-set win that ended late Friday, said it's way too early for him to think about his place in history — or about the so-called pressure to break through at the U.S. Open.
"For me, just to be here and have a chance to win the fourth is just an unbelievable thing," Nadal said. "When I was younger, seven years before or six years before or three years before, I never really thought I really could do that."