Top seed Simona Halep became the latest and perhaps biggest casualty at 2018 Wimbledon as the reigning Roland Garros champion was eliminated by Su-Wei Hsieh 3-6, 6-4, 7-5 in 2 hours, 20 minutes.
The world number 48 rallied from a 5-2 deficit in the final set to reach the fourth round of a major for the third time and first at the All-England Club.
It was also the Taiwanese's first victory over a top-ranked player.
Halep takes break-filled opening set
Hsieh is a very crafty player who plays with two hands off of both sides and can construct points as well as any player on tour, especially on grass.
Her serve, however, is a liability and it showed as the first five games of the match went the way of the returner, Halep with a slice of luck as Hsieh's backhand drifted wide after having to play the ball off of a net cord.
The world number one was nearly ahead by a double break in the seventh game, but a good wide serve and a high forehand volley putaway rescued the situation, the Taiwanese holding.
It was Halep's turn to save a break point in the very next game, a backhand that Hsieh tried to steer down the line just clipping the tape. That paved the way for a hold and she was a game away from the first set.
The Romanian did get another chance to secure another break and this time she was successful, Hsieh with a forehand that found the net, Halep struggling through to take a one-set lead.
Hsieh strikes back to level the match
Both players held fairly comfortably to start the second set, a rare occurrence in this match so far. Hsieh struck first in the third game, a brilliant backhand down the line giving her a 2-1 lead.
If the world number 48 could hold her serve enough, she would be in with a real chance of the upset, but her advantage was gone in the sixth game, Halep stinging a forehand winner to restore parity to the set at 3-3.
It was continuing to be a case of the Romanian's powerful baseline game against the Taiwanese's variety and court craft and in the ninth game, it was Hsieh back out in front, mixing up her angles beautifully until she drew a weak backhand reply on break point for a 5-4 lead.
Serving for the set, the world number 48 had something of an anomaly in this match: a love hold, Hsieh's full arsenal on display, a lob to get to 30-0, a short backhand to bring up three set points and her best serve of the match drawing an error to even the contest.
Halep jumps out to quick start in final set
The beginning of the third set closely resembled the start of the match. After Halep began with a routine hold, three straight breaks followed, the final of those going to the Romanian on her fifth chance, a lovely backhand down the line giving her a 3-1 lead, Hsieh barely able to get her racket on the ball.
Shades of the second set began to emerge, both players cruising on serve, of particular importance to Hsieh as she tried to conserve her energy for one last push.
Ultimately, Halep finished off the seventh game with her first ace for a 5-2 lead. Little did she know that would be her final game won in the match.
Hsieh wins last five games to capture career-defining victory
Hsieh was starting to hold with greater ease and she posted a love hold, forcing Halep to serve for the match at 5-3. The Romanian was quickly behind 15-40, but a forehand winner and backhand error from the Taiwanese brought the game back to deuce.
It was to be at the third time of asking, the world number 48 drove a crosscourt forehand past Halep, who thought the previous shot may have been long, to get back on serve.
She kept up the momentum, but only just. Halep would arrive at match point, summarily dismissed with a crisp backhand winner. The 12 point game was capped with the world number one floated a backhand long.
Another marathon game was to ensure, Hsieh with a chance to break after Halep wasn't close with a backhand. It was the Taiwanese who struck the decisive backhand to claim a 6-5 lead to serve for a monumental upset.
The Romanian isn't number one by accident and she was 15-40 ahead. In a final twist of irony, it was Hsieh's serve that saved the first break point and her impeccable defence saving the second.
Another strong serve got Hsieh to match point and when Halep's forehand found the bottom of the net, the upset was complete and the wildest first week Wimbledon has ever seen was brought to a close with a sensational victory for the remarkable Taiwanese.