Match ends, Chelsea 1(4), Aston Villa 1(3).
Reece James scored the winning penalty in a shootout as Chelsea reached the last 16 of the Carabao Cup at Aston Villa's expense.
The full-back fired home the Blues' final penalty to win the shootout 4-3.
A goal from young Villa forward Cameron Archer had ensured a draw in normal time, levelling with a header after Timo Werner had put the Blues ahead.
Chelsea will host Southampton in the last 16 of a competition they last won in 2014-15.
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Wednesday's result extends the reigning European champions' unbeaten start to the season, which has also seen them top the Premier League with 13 points from five matches.
It looked as though they were going to win the game in normal time when Werner rose in space to meet James' cross and head home his first club goal in 11 matches.
The German should have added to his tally soon after but dragged a shot from close range wide of the target.
But Villa, who had given as good as they got during the game, deservedly levelled when Archer showed brilliant technique to steer in a headed equaliser.
It made it four goals in two EFL Cup games this season for the 19-year-old, who scored a hat-trick in the 6-0 win over Barrow in the second round.
It was also the first goal from open play that Chelsea have conceded this season.
In the shootout, Ashley Young struck the crossbar with Villa's second penalty before Kepa Arrizabalaga saved their third from Marvelous Nakamba to hand the advantage to the home side.
Ben Chilwell then struck the bar to take it to the final set of penalties, but James made no mistake to seal the Blues' progress.
Chelsea boss Thomas Tuchel speaking to the club website: "It was a good game full of energy, good chances on both sides between two teams who tried everything to win.
"Aston Villa played very strong, like they did 10 days ago, and again today. We also did very good.
"We had many changes, the team had never played in this formation. This needs a bit of time on the field, but it was important we don't expect too much in terms of how we create chances."
Aston Villa assistant boss Craig Shakespeare to the club website: "We're disappointed to go out. We came here with a gameplan and we picked a team that needed minutes.
"Chelsea's superiority in terms of possession meant we had to hang in there at times in the second half.
"The overall performance and chances we created, the lads can be very, very pleased with.
"However, they're disappointed in the changing room to go out."
- 24JamesBooked at 90mins
- 31SarrBooked at 31mins
- 7KantéSubstituted forMountat 45'minutes
- 17SaúlSubstituted forLukakuat 76'minutes
- 22ZiyechSubstituted forBarkleyat 76'minutes
- 6Thiago Silva
- 2CashSubstituted forKonsaat 77'minutes
- 18YoungBooked at 86mins
- 8SansonSubstituted forChukwuemekaat 42'minutes
- 15TraoréSubstituted forPhilogene-Bidaceat 64'minutes
- 21El Ghazi
- Graham Scott
- Shots on Target
Penalty Shootout ends, Chelsea 1(4), Aston Villa 1(3).
Goal! Chelsea 1(4), Aston Villa 1(3). Reece James (Chelsea) converts the penalty with a right footed shot to the top left corner.
Goal! Chelsea 1(3), Aston Villa 1(3). Emiliano Buendía (Aston Villa) converts the penalty with a right footed shot to the bottom right corner.
Penalty missed! Still Chelsea 1(3), Aston Villa 1(2). Ben Chilwell (Chelsea) hits the bar with a left footed shot.
Goal! Chelsea 1(3), Aston Villa 1(2). Ezri Konsa (Aston Villa) converts the penalty with a right footed shot to the top right corner.
Goal! Chelsea 1(3), Aston Villa 1(1). Ross Barkley (Chelsea) converts the penalty with a right footed shot to the bottom right corner.
Penalty saved! Marvelous Nakamba (Aston Villa) fails to capitalise on this great opportunity, left footed shot saved in the bottom right corner.
Goal! Chelsea 1(2), Aston Villa 1(1). Mason Mount (Chelsea) converts the penalty with a right footed shot to the centre of the goal.
Penalty missed! Still Chelsea 1(1), Aston Villa 1(1). Ashley Young (Aston Villa) hits the bar with a right footed shot.
Goal! Chelsea 1(1), Aston Villa 1(1). Romelu Lukaku (Chelsea) converts the penalty with a left footed shot to the bottom right corner.
Goal! Chelsea 1, Aston Villa 1(1). Anwar El Ghazi (Aston Villa) converts the penalty with a right footed shot to the top right corner.
Penalty Shootout begins Chelsea 1, Aston Villa 1.
Second Half ends, Chelsea 1, Aston Villa 1.
Corner, Chelsea. Conceded by Carney Chukwuemeka.
Foul by Romelu Lukaku (Chelsea).
Ezri Konsa (Aston Villa) wins a free kick in the defensive half.
Corner, Chelsea. Conceded by Axel Tuanzebe.
Attempt missed. Ruben Loftus-Cheek (Chelsea) header from the centre of the box misses to the right. Assisted by Mason Mount with a cross following a corner.
Corner, Chelsea. Conceded by Axel Tuanzebe.
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