Igor Tudor's gamble to start Antonin Kinsky over Guglielmo Vicario in Tottenham's Champions League last-16 tie at Atletico Madrid spectacularly backfired, with Spurs thrashed 5-2 in the first leg.
The 22-year-old was selected in goal at the Estadio Metropolitano instead of the Tottenham No 1, having made just two starts in the Carabao Cup this season.
Tuesday's game marked his first Champions League start and it could not have gone any worse.
Questions will be asked of Tudor's team selection, especially as he hooked Kinksy inside 17 minutes with Spurs already 3-0 down after two catastrophic errors from the young goalkeeper.
Tudor failed to acknowledge Kinksy when he was replaced.
The goalkeeper had been at fault for Atletico's first goal after six minutes when his botched clearance ended with Marcos Llorente slotting home.
Minutes later, another slip allowed Atletico to double their lead. A forward pass from Llorente should have been dealt with by Micky van de Ven but he fell onto the surface. Antoine Griezmann took full advantage and stroked the ball into the back of the net.
But the calamities didn't end there.
Kinsky slipped again as he tried to send the ball out the other side of the box, allowing Alvarez to walk the third goal over the line.
Immediately, Vicario was sent out to warm up and, moments later, he came on to replace his team-mate, who went straight down the tunnel with two staff members in pursuit while Tudor stood motionless on the touchline.
The Italian stopper's first job was to push away an Atletico corner - but he could not stop Robin Le Normand nodding home the rebound. Despite Spurs' best efforts to hook it away, goal-line technology awarded the goal, which was quite clearly over the line.
But despite the calamity in defence, Spurs did look bright going forward, and pulled a goal back soon after for 4-1. It was well-worked too as Richarlison cut into the box, before finding Pedro Porro. His first touch took the ball around his defender, before firing home.
Spurs were lucky to end the first half with 11 men on the pitch. Van de Ven - who was sent off against Crystal Palace last week - flew in on a high challenge on David Hancko. The referee waved away the Atletico claims and VAR did check it for a red card, but nothing was given.
The second half was a quieter affair, but still had its own share of jaw-dropping moments. Twelve seconds after Jan Oblak saved a darting header from Richarlison, Atletico broke at the other end and scored their fifth as Alvarez slotted past Vicario's outstretched foot.
But even Atletico's veteran goalkeeper was not immune to an error in an incredible first leg. His own poor back pass went directly to Porro, who sent it on to Dominic Solanke to fire home as Spurs pulled back another goal late on.
It leaves them with a three-goal deficit to make up at the Tottenham Hotspur Stadium next Wednesday, sandwiched between a trip to Liverpool this weekend, live on Your Site. in their first leg on Tuesday.
Tudor went some way to explaining why he dropped Vicario for the 22-year-old Kinsky, calling Spurs 'fragile' and 'weak' at the start of the game.
He said: "It is very rare. I have coached 15 years and never done this. It was necessary to preserve the guy and to preserve the team. Incredible situation.
"Before the game it was the right choice. Where we are with pressure on Vicario, Toni is a very good goalkeeper. After this it is easy to say it was not the right decision.
"I was speaking with Toni after. He is a bright guy, good goalkeeper and unfortunately it happened in this big game, these big mistakes.
"The start of the game was too much for us. In this moment when we are fragile, when we are weak."
Tudor has remained coy on his position as Spurs head coach in the wake of a fourth damaging defeat since taking charge, just 24 days ago. Again he chose to reply "no comment", as he did last week, when asked if he is deserving of the role in his post-match press conference in Spain.
Asked if overseeing Spurs is the 'impossible job' right now, he replied: "I am not taking it that way. I recognised what we are and which problems we have. Every game something happens. It is difficult to explain.
I see the wish of the players to do well. Then when these things happen, in the moment we are in now, unfortunately, it is like that."
Commenting on what needs to happen ahead of facing Liverpool this weekend, he added: "I try to do my best. What a coach needs to do."
Your Site News' Michael Bridge in Madrid:
"You think you've seen it all but they'll have to be discussing his [Tudor's] future. It's very, very toxic. Some players will be unhappy with what happened during the game with Kinsky going off.
"I saw Joao Palhinha and Conor Gallagher running to console Kinsky - these are players that are worried about Kinsky's welfare.
"Igor Tudor didn't acknowledge Kinsky when he came off. It was the ultimate humiliation. There was a powerful tweet from David de Gea about it and I'm sure the players will be speaking to officials at Spurs.
"There has also been footage of Cristian Romero almost telling Tudor to take Kinsky off. I asked Tudor that and he denied it but if you look at the footage you do wonder if Romero did ask him to take him off.
"It's such a damaging defeat in so many ways. Tudor's future will come into question now. There has been no manager bounce and Spurs actually look worse. And it could get even worse before it gets better. Tudor was brought in to put fires out straightaway but more fires have been created."
Round of 16 second legs: March 17-18
Quarter-finals: April 7-8 and 14-15
Semi-finals: April 28-29 and May 5-6
Final: May 30 (Puskas Arena in Budapest, Hungary)
