Roger Federer advanced to the quarterfinals of the 2012 U.S. Open on Monday, after Mardy Fish withdrew from the fourth-round match between the two because of precautionary health concerns.

Fish had been sidelined for two months earlier this year because of an accelerated heartbeat, and had a medical procedure to remedy the issue in May.

Federer will now face the Czech Republic's Tomas Berdych in the quarterfinals. Berdych, the No. 6 seed in the tournament, advanced in straight sets over Nicolas Almagro, 7-6 (7-4), 6-4, 6-1.

The withdrawal is both unfortunate and disappointing for Fish, who advanced to the fourth round after pulling off a minor upset over France's Gilles Simon, winning 6-1, 5-7, 7-6 (7-3), 6-3.

Barring any upsets from this point forward, Federer will face Andy Murray in the semifinals, in a rematch of the 2012 Olympic gold medal mach.

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