Mason Mount was a picture of despair after missing from the penalty spot as Tottenham won a shoot-out at the end of an entertaining London derby to progress to the fifth round of the Carabao Cup.
Spurs had come back to equalise through Erik Lamela after Timo Werner had put Chelsea ahead with his first goal for the club, and with the sides even after 90 minutes, the tie went straight to penalties. The first nine takers all scored, leaving Mount needing to score the 10th to keep Chelsea in the cup.
The young midfielder’s shot hit the outside of the post, and Spurs were through, ultimately deserving winners after dominating the second half, having been second best for the opening 45 minutes.
As promised, Jose Mourinho rested some of his big-hitters including Harry Kane, Harry Winks, and Giovani Lo Celso, and gave a debut for former Real Madrid left-back Sergio Reguilon, while Edouard Mendy also made his first start in goal for Chelsea.
After a sterile opening quarter of an hour, it was Chelsea who made the breakthrough in the 19th minute. Reguilon lost the ball in midfield to Callum Hudson-Odoi, who fed Cesar Azpilicueta on the right. The Chelsea captain drew his compatriot Reguilon into a forlorn sliding challenge before crossing low for Werner to drill the ball low through a crowd of players and into the net.
It was the German's first goal for Chelsea, but his second here at the Tottenham Hotspur Stadium, having scored the winner for RB Lepizig from the penalty spot in the Champions League earlier this year.
Spurs did not have much to offer going forward, having started without a recognised striker, but Gedson Fernandes, one of their five midfielders, hustled an opening in the 23rd minute before Kurt Zouma made a timely tackle in front of Mendy.
Soon afterwards Mourinho and Lampard had a frank exchange of views on the touchline, demonstrating their was clearly no love lost between sorcerer and apprentice, who were so close during the Portuguese manager's two spells at Stamford Bridge.
The row seemed to fire up Tottenham, who finally started to make Mendy work. Erik Lamela cut in from the right and fired in a shot that Mendy parried, and when the loose ball was lobbed back in, the goalkeeper caught it under a muscular challenge from Steven Bergwijn. Callum Hudson-Odoi had a rare start on Chelsea's right wing, and after having an early snapshot saved by Hugo Lloris, made a surging run before half-time, only to be dispossessed by a fine sliding challenge from Reguilon, who atoned for his earlier error.
Spurs continued to press for an equaliser after the break. Bergwijn carved out a shooting chance but shot high and wide, before Reguilon brought the best out of Mendy, who made a superb save to tip the Spaniard's powerful drive over the bar.
Serge Aurier, restored at right wing-back in place of the rested Matt Doherty, shot wide and was then booked for a sliding challenge on Jorginho, and Japhet Tanganga was also cautioned as the action intensified.
Tottenham had plenty of possession and had Chelsea penned in ther own half for long periods, but no cutting edge, so Mourinho decided to go for broke, sending on first Pierre Emile Hojbjerg and then Kane as substitutes for the final 20 minutes. Aurier crossed for Reguilon at the far post, but the Spaniard's diving header was well wide.
Having not threatened Tottenham's goal for most of the second half, Chelsea suddenly had three good chances, but Lloris saved Werner's piledriver, Hudson-Odoi shot over the bar, and Mason Mount was stopped by Eric Dier on the edge of the penalty area.
Kane had one golden chance with ten minutes to go when he turned Fikayo Timori inside out to open up a shooting chance, but curled his effort too high.
Lampard countered with changes of his own, sending on Ngolo Kante, Tammy Abraham and Emerson in the closing stages.
It was Lamela who got a deserved equaliser in the 83rd minute. Reguilon crossed from the left, it sailed over a clutch of players and the Argentine controlled the ball at the far post before drilling it over the line.
That was the last meaningful action of the 90 minutes, before the tie went to a penalty shoot-out. Eric Dier, who'd earlier left the field to run to the dressing room for a brief spell, scored with Tottenham's first kick, and Abraham scored Chelsea's first. Lamela sent Mendy the wrong way, and then Azpilicueta did the same to Lloris. Hojbjerg, Jorginho, Lucas Moura and Emerson continued the 100 per cent record, Kane then made it 5-4 to Spurs, meaning Mount had to score to keep the game alive. His shot hit the outside of the post, Chelsea were out and Tottenham's players were left to celebrate a place in the fifth round.
Lloris 7; Tanganga 6 (Kane 70), Dier 7, Alderweireld 6; Aurier 7, Sissoko 6, Ndombele 8, Gedson 6 (Hojbjerg 63), Reguilon 7; Lamela 8, Bergwijn 6 (Moura 76)
Mendy 7; Azpilicueta 6, Tomori6, Zouma 7, Chilwell 7 (Emerson 66); Kovacic 6 (Kante 70), Jorginho 6, Mount 6; Hudson-Odoi 7, Giroud 6 (Abraham 76), Werner 8.