Defending champion Roger Federer lost 6-7 (5-7) 7-6 (7-5) 7-5 7-6 (7-5) to world number 116 Sergiy Stakhovsky in the second round at Wimbledon.
Seven-time winner Federer, 31, was made to look sluggish by his Ukrainian opponent, who played inspired serve-and-volley tennis on Centre Court.
It is Federer's earliest exit at Wimbledon since 2002, when he was beaten in the first round.
Federer's defeat is further good news for Britain's second seed Andy Murray.
Fifth seed and two-time champion Rafael Nadal was also on Murray's side of the draw but lost in the first round.
Federer's earliest defeat at Wimbledon since losing in the
first round in 2002
His earliest defeat at a Grand Slam event since losing in
the first round of the French Open in 2003
Ends Federer's run of 36 consecutive Grand Slam
quarter-final appearances, starting at Wimbledon in 2004
Federer's worst defeat at a Grand Slam (or any event)
since losing to world number 154 Mario Ancic in the first
round at Wimbledon in 2002
His first defeat by a player ranked outside the top 100
since losing to number 101 Richard Gasquet at Monte
Carlo in 2005
The earliest defeat for a defending Wimbledon men's
singles champion since Lleyton Hewitt lost to Ivo
Karlovic in the first round in 2003
And sixth seed Jo-Wilfried Tsonga withdrew from his second-round match because of an injury, meaning the highest seed left in Murray's half is 15th.
Federer's defeat meant it was also his earliest Grand Slam exit since losing in the first round of the French Open in 2003.
It also ended the 17-time major champion's run of 36 consecutive quarter-final appearances in Grand Slam events, which started at Wimbledon in 2004.
"When you play Federer at Wimbledon it's like you're playing two people," said Stakhovsky, "Federer and his ego.
"I hoped he wouldn't get too far away from me and I hung in there every game on my serve, trying to play for a tie-break.
"It was magic, I couldn't play any better today. Every important point I played well and I served and volleyed incredibly well."
The 27-year-old Stakhovsky's previous best display at Wimbledon was reaching the second round in 2011 while he has never gone beyond the third round at a Grand Slam event.
It was Federer's first defeat by a player ranked outside the top 100 since losing to 101-ranked Richard Gasquet at Monte Carlo in 2005.
It was also the earliest defeat for a defending Wimbledon men's singles champion since Lleyton Hewitt lost to Ivo Karlovic in the first round in 2003.