Canada's Milos Raonic is making a quarter-final exit at the Rogers Cup.
The sixth seed from Thornhill, Ont., dropped a 6-4, 6-7 (5), 6-3 decision to Spain's Feliciano Lopez before a surprised crowd at Rexall Centre.
Lopez is unseeded at the Masters 1000 series event and is ranked 25th in the world, 19 positions below Raonic.
Lopez will play either Switzerland's Roger Federer or Spain's David Ferrer in the semifinals on Saturday.
Jo-Wilfried Tsonga of France and Grigor Dimitrov of Bulgaria will meet in the other semifinal.
Tsonga defeated Andy Murray of Britain in the early quarter-final match while Dimitrov beat South Africa's Kevin Anderson.