New York, Sept 11: Many may be surprised by Roger Federer's untroubled progress towards becoming the oldest US Open champion in almost half a century, but not Federer himself.
The 34-year-old has glided into the semi-finals, where he will face Swiss compatriot Stan Wawrinka on Friday.
It will be his 10th New York semi-final as the five-time champion targets a record sixth US Open and 18th Grand Slam title.
"For many years I have tried to look at the big picture to hopefully still be playing at a high level at this age," said Federer, who would be the oldest winner of theUS Open since Ken Rosewall in 1970.
"So in some ways I am not surprised I am playing as well as I am."
Federer has not won a major since his seventh Wimbledon title in 2012, but came into the US Open on the back of a seventh Cincinnati title, defeating world number one Novak Djokovic in the final.
It was his 87th career title and pushed his on-court earnings to almost $94 million.
His form in New York has been just as impressive, dropping serve just twice and not yet having lost a set.
Despite his Grand Slam title drought -- the longest of his career -- Federer has not been afraid to keep innovating.
In recent years, he has experimented with a larger racquet, brought in former world number one Stefan Edberg to work alongside long-time coach Severin Luthi and radically altered his playing schedule.
The US Open is only his 13th tournament of the year.
He has also invented a new tactic, the 'SABR' or 'Sneak Attack By Roger,' which is his chip-and-charge on an opponent's second serve.
After his 87-minute quarter-final demolition of Richard Gasquet on Thursday, Federer also said he was sleeping more up to 10 hours a day to maintain his competitive level. AFP