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.
Meanwhile, non-league Kidderminster Harriers were seconds away from one of the biggest shocks in FA Cup history until Declan Rice rescued West Ham as the Premier League side progressed to the fifth round 2-1 after extra time.
Sixth-tier Kidderminster sit 113 places below David Moyes’ men, who are pushing for a place in next season’s Champions League.
But the fragility in the Hammers’ squad without Rice and Michail Antonio was exposed as Harriers were good value for the lead given to them by Alex Penny’s early goal for much of the 90 minutes.
The defender smashed into an unguarded after the Hammers failed to deal with Omari Sterling’s free-kick.
Moyes sent on Rice at half-time among five changes during the second half, but the home side looked set to hold on until the England midfielder took matters into his own hands.
Rice charged forward from midfield in the first minute of stoppage time, cut inside and blasted the ball high into the roof of the net.
Even then the visitors laboured for 30 minutes of extra time until striking in stoppage time once more to avoid the risk of a penalty shootout.
Jarrod Bowen was left with the simple task of tapping home from close range after Kidderminster ‘keeper Luke Simpson denied Aaron Cresswell from point-blank range.