Rafael Nadal's long winning run was halted by fellow-Spaniard Feliciano Lopez at Queen's Club on Friday when he lost 7-6, 6-4 in the quarter-finals.
It was Nadal's first defeat since he lost to Andy Roddick in Miami on April 2, after which he embarked on a 24-match unbeaten sequence which included a fifth French Open on Sunday.
Lopez, one of the few players comfortable coming in after his first serve, kept world number one Nadal under pressure throughout the centre court contest and took his chances to claim the first victory for a Spaniard over Nadal since Juan Carlos Ferrero beat him in Rome two years ago.
Nadal showed no obvious signs of the muscle injury that required on-court treatment on Thursday but his precision groundstrokes were slightly off-beam on a slick court which suited Lopez's attacking style.
Lopez will face either France's Michael Llodra or American Mardy Fish in the semi-finals.
Fish accounted for defending champion Andy Murray earlier.
Murray, the third seed, was furious on Thursday evening when Fish walked off at 3-3 in the deciding set claiming the light was too poor to continue and his mood was not helped as he returned to lose 6-4, 1-6, 7-6.