American Mardy Fish has been forced to pull out of the US Open for health reasons.
The 30-year-old had been due to take on world number one Roger Federer in round four later today.
However, a so-far unspecified medical complaint has forced the world number 25 to withdraw at short notice.
As a result, Federer has now qualified for his 34th consecutive quarter-final at a Grand Slam event.
He will now face either Tomas Berdych or Nicolas Almagro for a place in the semis.
