(CNN) -- Top seed Rafael Nadal crashed out of the Shanghai Masters Thursday to Germany's Florian Mayer, beaten in straight sets 7-6 6-3.
The Spaniard could not recover from losing the first set tiebreaker 7-5 and was broken twice in the second set by his 15th-seeded opponent, who said it was the "biggest win of his career."
Nadal summed it up after the match: "He played really well, I didn't," he told AFP.
"I felt that I was not playing badly from the baseline. But my return, when he was serving the first serve, was terrible tonight. I only won four points in the whole match on his first serve."
Mayer will next play Spain's Feliciano Lopez, who completed the quarterfinal lineup after a straight sets win over sixth seed Tomas Berdych.
Lopez broke the Czech once in each set for a 6-4 6-4 victory in one hour and 21 minutes.
Earlier, defending champion Andy Murray had to battle past 13th seed Stanislas Wawrinka in a bad-tempered three-set match with the beaten Swiss player warned for racket abuse.
World number four Murray raced through the first set but was broken in the second as Wawrinka leveled.
Murray then raced to a 5-0 lead in the decider and despite losing his service again closed out a 6-4 3-6 6-3 win as he bids for his third straight title after winning in Thailand and Japan.
"I got myself pumped up right at the beginning of the third set. I think it was important," said Murray.
Spain's David Ferrer beat compatriot Juan Carlos Ferrero 1-6 7-5 6-2, saving three match points in the second set. The victory means he becomes the fifth player to qualify for the season-ending ATP World Tour Finals.
Andy Roddick of the United States beat Spanish seventh seed Nicolas Almagro of Spain 6-3 6-4 to continue his fine form in China, while Ukrainian 12th seed Alexandr Dolgopolov ended the run of Australian teenager Bernard Tomic as he won 5-7 6-1 6-0.
Tomic's fellow Australian Matthew Ebden had better luck as he upset eighth seed Gilles Simon of France 6-2 2-6 7-6.