Chelsea needed extra time and late drama on Saturday to see off lower league opposition 2-1 to reach the last 16 after Plymouth missed a late penalty at Stamford Bridge.
Chelsea were without manager Thomas Tuchel, who has tested positive for coronavirus.
And a star-studded Blues line-up made life difficult for themselves before jetting off to the Club World Cup in Abu Dhabi.
Macaulay Gillesphey nodded the League One side into the lead after just eight minutes.
The Plymouth goal led a charmed life as Mateo Kovacic and Callum Hudson-Odoi hit the bar before Cesar Azpilicueta’s inventive finish levelled just before half-time.
An expected Chelsea onslaught in the second half failed to materialise and they had to wait until stoppage time at the end of the first half of extra time to go in front when Marcos Alonso slotted home Kai Havertz’s cross.
However, the drama did not end there as Plymouth were awarded a penalty with seconds to go in extra time.
Kepa Arrizabalaga has been brought on in the past by Tuchel for shootouts as a penalty specialist and the Spaniard ensured there was not a shootout when he saved Ryan Hardie’s spot-kick.