Roger Federer has said that he is 'shocked' by the number of players forced to retire during this year's US Open.
The amount of withdrawls went up to 18 on Saturday, creating a new record.
"Could some guys finish the matches? I'm sure, but they didn't decide to," said the 30-year-old.
"For me it is shocking to see so many retirements. I have never retired in my whole life, except once when I played against [James] Blake in Paris, but I didn't even walk on to the court.
"For me, it doesn't matter how bad I'm feeling, I will be out there and giving it a try, because you never know what's going to happen."
The five-time US Open winner is through to the fourth round of the event, where he will face Argentina's Juan Monaco.
