American Mardy Fish beat world number two Rafael Nadal for the first time in his career and booked a spot in the semi-finals of the Cincinnati Tennis Open where he will face Britain's Andy Murray.
Fish entered the match having lost his prior six meetings with the Spaniard but battled for a 6-3 6-4 win against Nadal, who was dealing with a foot problem and struggled against his opponent's serve.
The seventh-seeded American, who produced 12 aces, made the decisive break to go up 3-2 in the second set when Nadal went long on a return.
After having some treatment on his foot, Nadal found some extra power as he fought in vain to break back.
Fish's powerful serve was on display in the final game when he served to love for the match.
Murray enjoyed a comfortable 6-3 6-3 win over France's Gilles Simon in his quarter-final.
The Scot, who has won the last seven meetings with 10th seed Simon, exchanged breaks with his opponent to start the match but was in control the rest of the way.
Simon was the only player outside the top eight seeds to reach the quarter-finals after a three-set win over Spain's David Ferrer that lasted over three hours.
World number one Novak Djokovic is in action later against France's Gael Monfils, while number three Roger Federer has a tricky test against Czech Tomas Berdych, who beat him twice last year.