Hot American Mardy Fish upset former world No. 1 Rafael Nadal in Friday's quarterfinal action at the $2.43 million Western & Southern Open, an ATP Masters and U.S. Open Series event.

The seventh-seeded Fish took it to the second-seeded Nadal for a crowd- pleasing 6-3, 6-4 victory on the hardcourts at the Lindner Family Tennis Center. Fish prevailed in 1 hour, 39 minutes by smacking 12 aces, holding his big serve throughout, and breaking the mighty Spaniard on two occasions on Day 6. Fish ended the bout with an outstanding forehand cross-court winner.

Fish has yet to lose his serve this week.

The 29-year-old Fish recorded his first career victory against Nadal in seven tries and will now appear in his fourth straight semifinal. The American slugger captured the U.S. Open Series by winning on Friday and will now at least double his prize money at the 2011 U.S. Open.

Fish was last week's Masters runner-up to high-flying Novak Djokovic in Montreal and last year's Cincy runner-up to the great Roger Federer.

The Minnesota native Fish's semifinal opponent on Saturday will be former Cincinnati champ Andy Murray. The American is 4-3 lifetime against the Brit, including a quarterfinal victory here a year ago.

A fourth-seeded Murray peppered 10th-seeded Frenchman Gilles Simon 6-3, 6-3 on Friday. Murray is now a lopsided 7-1 lifetime against Simon, including seven straight wins.

The world No. 12 former top-10 star Simon was a champion in Hamburg last month.

The 2011 Australian Open runner-up Murray captured this Cincinnati tournament back in 2008.

This week's winner will collect $496,000.