Nottingham Forest stunned woeful Chelsea 3-1 at Stamford Bridge to go six points clear of the Premier League relegation zone and send a warning shot to Aston Villa ahead of Thursday's Europa League semi-final second leg.
As the home fans raged at a sixth-straight Premier League defeat for Chelsea, which puts their own European qualification chances in serious doubt, the visitors celebrated an emphatic victory which few would have predicted when the team sheets came out.
Vitor Pereira made eight changes to his starting XI with the Villa game seemingly on his mind. But it turned out to be a masterstroke of a gameplan from the head coach, with his fringe players first seizing their opportunity before his star men saw the team to victory. Forest's prospects on both domestic and European fronts have been boosted.
Chelsea stay ninth and are now unable to achieve fifth place in the Premier League, which would secure Champions League qualification. If Villa win the Europa League and finish fifth, sixth would be enough to reach Europe's elite club competition and the Blues are four points off Bournemouth, who hold that spot.
But any European football at all is far from certain for this side. The FA Cup could yet provide them a gateway to the Europa League but their semi-final win at Wembley last time out was supposed to reignite their season. They fell back into their bad ways here.
Any suggestion Forest had switched priorities away from the Premier League was blown out of the water after just 97 seconds, when Taiwo Awoniyi rose to head in Dilane Bakwa's cross.
The marking from the Chelsea defence was non-existent and, after Enzo Fernandez struck a post as the home side scrambled for a response, there was more dreadful defending, with Malo Gusto pulling Awoniyi's shirt in the box to hand Igor Jesus the chance to double the lead on 15 minutes.
Chelsea had their own opportunity to score a penalty just before half-time when there was a nasty clash of heads between Forest defender Zach Abbott and Blues Premier League debutant Jesse Derry, but Cole Palmer saw his spot-kick saved by Matz Sels.
It was just the second Premier League penalty he's failed to score in 20 attempts but the circumstances were difficult. After almost 10 minutes of treatment on the pitch, 18-year-old Derry had to be stretchered away and taken to hospital for precautionary checks.
Levi Colwill came on for his first Chelsea appearance of the campaign at half-time, having overcome the ACL injury he suffered on the first day of pre-season. But there was also a significant triple change from Forest, with Morgan Gibbs-White, Elliot Anderson and Nikola Milenkovic sent on.
Pereira's call to introduce his big names looked inspired when Anderson played Gibbs-White through to tee up Awoniyi for Forest's third just seven minutes into the second half.
Awoniyi was narrowly onside. Joao Pedro was spotted to be narrowly offside by VAR when he thought he'd pulled one back for Chelsea on 73 minutes.
The Brazilian did eventually get on the scoresheet with a brilliant overhead in stoppage time as the home side piled on the pressure. But it was about the only thing that went right for Chelsea, on a day where everything turned to gold for Pereira and Forest.
Interim Chelsea boss Calum McFarlane:
"Really disappointed with the performance, disappointed with the result, I don't think we ever got to our level today that we know we're capable of.
"I thought the first 15 minutes we were nowhere near the level we needed to be. The early goal was a bit of a sucker punch and we didn't seem to really recover from that moment.
"It was a three vs one at the back post. We know that they like to cross to the back post, we know that the No 9 likes to peel to the back post and we should defend that moment better. Really disappointing. I thought we defended that moment really well [against] Leeds at Wembley and I just don't think we recovered from that moment well enough.
"When we did recover and we had moments, Enzo hits the post, Cole misses a penalty, Joao's offside goal... when you start that badly, you need those moments to go your way, to give you a chance to fight back into the game.
"The first 15 minutes was unacceptable."
Jamie Carragher on Your Site:
"It's shocking and it comes from the top.
"There's five or six really top players on the pitch today and they've been beaten by Nottingham Forest's B team.
"Less than 12 months ago, they were taking PSG to the cleaners.
"There's no connection between the players and the staff, the players and the fans.
"In some ways, it's a good thing because it tells you that football isn't just all about spending money, buying players and this revolving door.
"It's about creating togetherness and there's nothing there. They look like a broken football club right now."
Nottingham Forest could be sweating on the availability of Morgan Gibbs-White for Thursday's Europa League semi-final second leg at Aston Villa after he was taken off with a head injury in the second half.
Gibbs-White collided with Chelsea goalkeeper Robert Sanchez, which saw blood on Gibbs-White's face. The pair both walked off with bandages around their heads.
"Gibbs-White has a deep cut but he's a fighter, he has a strong mentality," said Forest boss Vitor Pereira. "I hope our medical department can do magic to put him in condition. Because he is important for us. I said to him you don't need to head the ball, just play. We'll see."
Concussion protocols could mean Gibbs-White may miss out on Thursday's trip to Villa Park, where Forest take a 1-0 first-leg lead, but Pereira said he was confident concussion would not be an issue.
Nottingham Forest boss Vitor Pereira to Your Site:
"The only thing I am sad about is the injury to Morgan Gibbs-White. I said we can change the players but the spirit will be there, and we will compete for the three points.
"We want to keep our future in our hands - and to do that we have to win games. Today, the players proved again the spirit, the quality and the organisation. I am very happy for my players and the supporters.
"We showed again strong spirit and that this is a special group. It is difficult to deal with four different managers, methodologies and tactical demands. It is difficult to keep them united, with friendship, and they are one of the best groups that I have worked with in my career."
