Leeds United suffered a humiliating FA Cup third-round exit as League Two Crawley Town outplayed their Premier League opponents to win 3-0 at Broadfield Stadium on Sunday.
Leeds sit 12th in the Premier League after a fine first season back in the top-flight, but manager Marcelo Bielsa paid the price for making seven changes at The People's Pension Stadium in leafy Sussex.
On a fairytale day for Crawley, it was fitting that Nick Tsaroulla should open the scoring with his first career goal in the 51st minute.
Ashley Nadesan's low shot crept under Kiko Casilla's weak attempted save to double Crawley's lead two minutes later.
Jordan Tunnicliffe forced the ball into the roof of the net from close-range in the 70th minute.
Since the Football League's fourth tier was added in 1958, this was only the second time a top-flight side had lost by three or more goals to opposition from that level in the FA Cup.
"You have to enjoy these games. You work hard enough for it," Crawley boss John Yems said.
"These players have got a lot to prove to the clubs who have released them and we've showed what we can do against a really good side.
"Let's see who we get in the next round and enjoy the moment."
It is not the first time Leeds have endured FA Cup ignominy after Don Revie's stars were famously eliminated by Colchester in 1971, while the club's 2008 side were embarrassed by Histon and the 2017 squad lost to Sutton.
Bielsa's men have made an impressive start to life back in the top-flight after a 16-year absence with the Argentine's attacking brand of football winning plenty of admirers.
But Bielsa is still yet to win an FA Cup tie in his three seasons in charge and was punished for resting a number of his key men.
Illan Meslier, Stuart Dallas, Luke Ayling, Mateusz Klich and Patrick Bamford were left out and in-form Crawley took advantage to extend their own unbeaten run to 10 games in all competitions.
Bielsa made three substitutions after a goalless first-half, but rather than kick the visitors' into gear, it was Crawley who took control in the second half.
"I can't find my words right now. We are really disappointed and it wasn't the result that we wanted," Leeds midfielder Ezgjan Alioski told BBC Radio 5 Live: "Especially me I'm really sad, we took the game really seriously and we wanted to win and go on a run so it is disappointing.
"Crawley played the game of their lives, and congratulations, and to beat us 3-0, I still can't believe it.
"The manager said what he wanted to say. It's important for every player to know what this means. He is sad, and the players are sad."
Crawley could even afford the luxury of handing a debut to reality TV star Mark Wright in stoppage time.
Wright, who started his career at Arsenal and Tottenham before going into television, is making a documentary with the club to see if he can make it as a professional player.
Chelsea, eight-time winners of the FA Cup and runners-up last season, showed Leeds how to deal with an upset threat as they thrashed League Two team Morecambe 4-0 at Stamford Bridge.
Two-time world heavyweight boxing champion Tyson Fury has a gym at Morecambe's Mazuma Stadium, but it was Chelsea who delivered the knockout blows.
Mason Mount marked his 22nd birthday in memorable fashion as the midfielder fired in from 25 yards in the 18th minute.
Werner finally got on the scoresheet in the 44th minute, bundling home after Kai Havertz headed into his path.
Callum Hudson-Odoi struck in the 49th minute and Havertz got the fourth in the 85th minute.
