Federer into US Open last eight as Fish pulls out

World number one Roger Federer received a walkover into the US Open quarter-finals Monday when America\'s Mardy Fish withdrew from their last-16 tie due to \"health reasons\", an event spokesman said. Five-time champion Federer will face either Czech sixth seed Tomad Berdych or Spanish 11th seed Nicolas Almagro for a place in the semi-finals. It will be the top seed\'s 38th Grand Slam quarter-final. \"Mardy Fish has withdrawn for health reasons,\" said the spokesman. Fish, 30, missed two months of the season earlier this year because of a heart problem. He was hospitalised after the Miami Masters in March when his heart rate increased to three times its normal resting rate. The American then underwent a procedure called a cardiac catheter ablation in Los Angeles on May 23 to correct faulty wiring in his heart.