Andy Roddick's hopes of making a second successive Wimbledon final ended as he was stunned 4-6 7-6 (7-3) 7-6 (7-4) 6-7 (5-7) 9-7 by unseeded Yen-Hsun Lu.
The world number 82 produced a superb performance and held off a typically spirited comeback from the fifth seed.
Lu led 3-0 in the fourth set tie-break but Roddick hit back to level matters.
Roddick had a break point to lead 5-4 in the fifth but Lu, from Taiwan, saved it and went on to become Asia's first Grand Slam quarter-finalist since 1995.
His performance emulated that of Japan's Shuzo Matsuoka, who reached the last eight at Wimbledon before losing to Pete Sampras.
Lu had never previously progressed beyond the third round of a Grand Slam nor made it past the second round at SW19 in six appearances.
He faced a formidable task against the American, whose Wimbledon record boasts three final appearances, one semi-final and one quarter-final.
Roddick took the first set with the only break point out on Court Two but Lu took the next two sets, neither of which featured a break point, on tie-breaks to edge ahead.
There were also no break points in the fourth set which again needed a tie-break to settle it and after Roddick put a backhand long and Lu held his serve twice, he seemed on the verge of a famous victory.
However, nerves may have played a part as after a Roddick ace, Lu put two forehands long to see his lead disappear. The fifth seed then moved ahead and an ace put him 5-4 up.
Roddick earned a set point when Lu netted another forehand and the American then produced his 11th ace of the set and 29th of the match to level the contest at two sets apiece.
The fifth set was understandably tight but Roddick had his chance to move ahead in the ninth game only for Lu to save a break point and go on to hold.
The pressure was now on the 27-year-old as every service game was to keep him alive in the match.
It finally told in the 16th game as Lu played a superb passing shot on his first match point to wrap up a memorable triumph.
Roddick praised Lu after the match but pinpointed errors in his own game, saying: "My returning was really bad.
His performance emulated that of Japan's Shuzo Matsuoka, who reached the last eight at Wimbledon before losing to Pete Sampras.
Lu had never previously progressed beyond the third round of a Grand Slam nor made it past the second round at SW19 in six appearances.
He faced a formidable task against the American, whose Wimbledon record boasts three final appearances, one semi-final and one quarter-final.
Roddick took the first set with the only break point out on Court Two but Lu took the next two sets, neither of which featured a break point, on tie-breaks to edge ahead.
However, nerves may have played a part as after a Roddick ace, Lu put two forehands long to see his lead disappear. The fifth seed then moved ahead and an ace put him 5-4 up.
Roddick earned a set point when Lu netted another forehand and the American then produced his 11th ace of the set and 29th of the match to level the contest at two sets apiece.
The fifth set was understandably tight but Roddick had his chance to move ahead in the ninth game only for Lu to save a break point and go on to hold.
The pressure was now on the 27-year-old as every service game was to keep him alive in the match.
It finally told in the 16th game as Lu played a superb passing shot on his first match point to wrap up a memorable triumph.
Roddick praised Lu after the match but pinpointed errors in his own game, saying: "My returning was really bad.
"I served well - I wasn't broken until the final game of the match and hadn't been broken since the first set against Michael Llodra.
"Through the first three sets I was playing horrendously, really badly. I think the fifth set was the best set I played as I was hitting the ball well and making him struggle to get through service games sometimes, but when you dig yourself a hole it is hard to get out when you have given them confidence.
"Through the first three sets I was playing horrendously, really badly. I think the fifth set was the best set I played as I was hitting the ball well and making him struggle to get through service games sometimes, but when you dig yourself a hole it is hard to get out when you have given them confidence.
