Nine spot-kicks were converted with the minimum of fuss, so Mason Mount had to score, but the midfielder’s effort clipped the outside of the post and went wide. It brought to an end our four-game winning streak against our north London rivals, and was made all the more frustrating considering the timing of Tottenham’s equaliser.

During regulation time, Werner had given us the lead with his maiden Blues goal, a confident finish from 18 yards out midway through a first half we largely dominated. Cesar Azpilicueta did brilliantly to set him up.

Tottenham were much improved after the interval and Edouard Mendy, on debut, did very well to deny Sergio Reguilon an equaliser. Our new Senegalese stopper had also kept out Erik Lamela in the first half.

As the contest opened up, we had chances to put the tie beyond doubt, but they were not taken and when another opportunity came Tottenham’s way with six minutes left, Lamela made no mistake.

So to penalties it went and after a flawless set of five from the home side, and four confident Chelsea efforts, Mount’s miss proved the deciding factor, ending our interest in this competition at the fourth round stage for the second straight season.

The selection

In total there were eight changes to the side that started at West Brom, one of which was Mendy. Ben Chilwell made his full Chelsea debut at left-back, and there were also starts for Fikayo Tomori, Callum Hudson-Odoi and, for the first time this term, Olivier Giroud.

Tottenham had a debutant of their own, their less high-profile signing from Real Madrid this summer, Reguilon.

Off the mark

The opening quarter-of-an-hour passed without any goalmouth incident at all, but our 80.2 per cent share of possession in that period suggested the pattern of the tie had been set. Tottenham, using a 5-3-2 shape, were happy to contain and try and release Erik Lamela and Steven Bergwijn on the counter, with the Blues seeking space between the lines from which to threaten.

Exactly that happened with 17 minutes gone. Patient probing made space for Chilwell down the left, and his cutback reached Hudson-Odoi, who hooked a left-footed shot too close to Hugo Lloris from 10 yards out.

We would not have to wait long to celebrate the opening goal; just another 100 seconds, in fact. Azpilicueta dispossessed Reguilon on halfway and foraged into the vacant space. Reguilon came flying in to try and win the ball back, but Azpi sold him a dummy and centred. Werner had floated into space on the edge of the box, and with the minimum of fuss the German drilled his shot through a crowd of bodies and into the bottom corner. It was an impressive way to open his Chelsea account.

Tottenham responded with their first meaningful attack and nearly a quick leveller after we lost possession, but Kurt Zouma recovered magnificently to tackle Gedson Fernandes cleanly as he went to shoot.

Edouard into the action

Mendy punched the resulting corner away, and after a couple of confident catches he made his first save in a Chelsea shirt 10 minutes before the break, keeping a low Lamela shot out with his feet after Spurs had worked an opening down our left.

Before long we had regained control of what was at times a feisty London derby, the absence of VAR helping the flow of the game. Hudson-Odoi was a particular nuisance down the right, and though clear opportunities remained at a premium, the Blues could be content with a much better first-half showing than at the weekend.

Bergwijn sliced over from range when play restarted as Tottenham came out with a little more urgency, and then Mendy showed what he can do with an excellent reflex save to tip Reguilon’s shot over the bar, Aurier’s cross having come all the way across the box.

Next it was Tomori to the rescue, cleanly tackling Bergwijn who was trying to beat him on the outside. In truth Chelsea hadn’t really got going since the break, so a couple of Tottenham yellows in quick succession on the hour provided a welcome breather.

With 24 minutes left, Emerson replaced Chilwell, who had enjoyed a solid full debut. Shortly after N’Golo Kante came on for Mateo Kovacic, while Harry Kane entered the fray for Tottenham as they sought a late equaliser.

Aurier to Reguilon again proved a useful combination for the home side, but this time the Spaniard nodded well wide with a stooping back-post header.

On 72 minutes, Kante stole the ball deep inside enemy territory allowing Mount to pick out Werner in space, but Lloris got down low to deny him and us a second that would surely kill the tie.

The next two chances were ours, too. First, a glorious long Jorginho pass released Hudson-Odoi, who cut inside and fired over, and then sub Tammy Abraham freed Mount, whose pass in Werner’s direction was intercepted.

Ten minutes remained, in which we were to be punished for our profligacy. Although Kane missed the target when many would have fancied him to find the top corner, Spurs did draw level in the 84 minute. Reguilon’s left-wing cross was allowed to reach Lamela, who couldn’t miss from point-blank range.

The closing stages were tight and tense, a blocked Werner shot in added time the only effort of note, so penalties it was to decide this London derby.

Mendy and Lloris were both continually sent the wrong way. Abraham, Azpilicueta, Jorginho and Emerson all notched efficiently for us, but Tottenham’s five successes meant Mount couldn’t miss, which he did, the ball tickling the left-hand post on its way wide.

What's next?

The Blues have another London derby up next, a Saturday lunchtime meeting with Crystal Palace at Stamford Bridge. That's our final game before the October international break.

Chelsea (4-2-3-1): Mendy; Azpilicueta (c), Tomori, Zouma, Chilwell (Emerson 66); Jorginho, Kovacic (Kante 70); Hudson-Odoi, Mount, Werner; Giroud (Abraham 76).Unused subs Kepa, James, Barkley, Havertz.Scorer Werner 19Booked Kovacic 45+2, Jorginho 83

Tottenham (5-3-2): Lloris (c); Aurier, Tanganga (Kane 70), Alderweireld, Dier, Reguilon; Fernandes (Hojberg 63), Sissoko, Ndombele; Lamela, Bergwijn (Moura 76).Unused subs Hart, Davies, Sanchez, Doherty.Scorer Lamela 83Booked Aurier 59, Tanganga 61

Penalties: Dier scored, Abraham scored, Lamela scored, Azpilicueta scored, Hojberg scored, Jorginho scored, Moura scored, Emerson scored, Kane scored, Mount missed.

Referee Lee Mason