Chelsea progressed to the quarter-finals of the Carabao Cup as they beat Premier League rivals Southampton on penalties after a 1-1 draw.
Reece James scored the decisive spot-kick for the league leaders after Theo Walcott and Will Smallbone failed to hit the target with their efforts for the Saints.
Both sides rung the changes for the tie, with Chelsea bringing in six different players from the 7-0 Premier League win against Norwich at the weekend while nine players came in for the visitors.
The hosts settled better into their rhythm and took the lead a minute before half time when Kai Havertz headed home his third goal of the season from a corner.
However, Southampton responded two minutes after the restart when Che Adams stabbed in from close range after Kepa spilled Kyle Walker-Peters' shot.
The goals brought the game to life as play then swung quickly from one end to the other.
Fraser Forster prevented the hosts from regaining the lead when he tipped over a James drive following a short free-kick, while substitute Shane Long headed wide for the visitors.
Smallbone almost marked his return to the first team after nine months out following an ACL injury with the winner, but his late header was saved by Kepa, who then produced two brilliant stops in stoppage time to deny Lyanco and Mohammed Salisu.
Those proved crucial as Chelsea came out on top in the penalty shootout to keep themselves firmly in the hunt for silverware this season.
The quarter-final draw is on Saturday at 10:30 BST.Relive Tuesday's Carabao Cup action
High-flying Blues get the job doneKai Havertz had put Chelsea ahead before half time
The Blues have enjoyed a fine start to the campaign both at home and in Europe as they sit top of the Premier League and have won two of their three games so far in the Champions League.
However, with games coming up thick and fast, boss Thomas Tuchel understandably opted to give some of his first-team players a rest and those on the fringes a chance to impress.
There were mixed displays from those who came in, Kepa caught the eye with his crucial double save and Saul Niguez twice came close to opening his goal account for the club.
However, Ross Barkley - making his first start of the season - and Hakim Ziyech were largely anonymous and taken off with 23 minutes to go.
It is the second time this season in the League Cup that Chelsea have needed penalties to progress after they edged Aston Villa 4-3 in the previous round, but ultimately they got the job done.
Tuchel will have found this a useful opportunity to learn more about his players as the Blues continue their fight for success in numerous competitions.
Player of the match
with an average of 7.45
Squad number29Player nameHavertz
Squad number19Player nameMount
Squad number21Player nameChilwell
Squad number14Player nameChalobah
Squad number24Player nameJames
Squad number20Player nameHudson-Odoi
Squad number8Player nameKovacic
Squad number18Player nameBarkley
Squad number3Player nameAlonso
Squad number22Player nameZiyech
Squad number31Player nameSarr
Squad number1Player nameArrizabalaga
Squad number17Player nameSaúl
Squad number44Player nameForster
Squad number10Player nameAdams
Squad number6Player nameOriol Romeu
Squad number17Player nameS Armstrong
Squad number22Player nameSalisu
Squad number21Player nameLivramento
Squad number4Player nameLyanco
Squad number9Player nameA Armstrong
Squad number7Player nameLong
Squad number2Player nameWalker-Peters
Squad number23Player nameTella
Squad number27Player nameDiallo
Squad number19Player nameDjenepo
Squad number20Player nameSmallbone
Squad number43Player nameValery
Squad number32Player nameWalcott
Formation 3-4-2-11Arrizabalaga24James14Chalobah31Sarr20Hudson-Odoi8Kovacic17Saúl3Alonso22ZiyechSubstituted forMountat 67'minutes18BarkleySubstituted forChilwellat 67'minutes29Havertz
Formation 3-4-344ForsterBooked at 90mins43Valery4Silveira Neves Vojnovic22Salisu2Walker-Peters27DialloBooked at 23minsSubstituted forRomeuat 77'minutes17S ArmstrongSubstituted forSmallboneat 77'minutes19DjenepoBooked at 80minsSubstituted forLivramentoat 83'minutes23TellaSubstituted forWalcottat 67'minutes10AdamsSubstituted forLongat 66'minutes9A Armstrong
Match ends, Chelsea 1(4), Southampton 1(3).
Penalty Shootout ends, Chelsea 1(4), Southampton 1(3).
Goal! Chelsea 1(4), Southampton 1(3). Reece James (Chelsea) converts the penalty with a right footed shot to the bottom right corner.
Goal! Chelsea 1(3), Southampton 1(3). Oriol Romeu (Southampton) converts the penalty with a right footed shot to the centre of the goal.
Goal! Chelsea 1(3), Southampton 1(2). Ben Chilwell (Chelsea) converts the penalty with a left footed shot to the bottom right corner.
Penalty missed! Bad penalty by William Smallbone (Southampton) right footed shot is just a bit too high. William Smallbone should be disappointed.
Goal! Chelsea 1(2), Southampton 1(2). Callum Hudson-Odoi (Chelsea) converts the penalty with a right footed shot to the bottom left corner.
Goal! Chelsea 1(1), Southampton 1(2). Shane Long (Southampton) converts the penalty with a right footed shot to the bottom left corner.
Penalty saved! Mason Mount (Chelsea) fails to capitalise on this great opportunity, right footed shot saved in the top left corner.
Penalty missed! Still Chelsea 1(1), Southampton 1(1). Theo Walcott (Southampton) hits the left post with a right footed shot.
Goal! Chelsea 1(1), Southampton 1(1). Marcos Alonso (Chelsea) converts the penalty with a left footed shot to the bottom right corner.
Goal! Chelsea 1, Southampton 1(1). Adam Armstrong (Southampton) converts the penalty with a right footed shot to the top left corner.
Penalty Shootout begins Chelsea 1, Southampton 1.
Second Half ends, Chelsea 1, Southampton 1.
Attempt saved. Malang Sarr (Chelsea) left footed shot from outside the box is saved in the top right corner.
Corner, Southampton. Conceded by Trevoh Chalobah.
Attempt blocked. Oriol Romeu (Southampton) right footed shot from outside the box is blocked.
Corner, Southampton. Conceded by Kepa Arrizabalaga.
Attempt saved. Mohammed Salisu (Southampton) header from the centre of the box is saved in the top right corner. Assisted by William Smallbone with a cross.
Corner, Southampton. Conceded by Kepa Arrizabalaga.