Plymouth's Ryan Hardie missed a late penalty as Chelsea survived a huge scare to defeat the League One side in the FA Cup fourth round.
Macaulay Gillesphey's early header from Jordan Houghton's cross sent the 6,000 travelling Argyle fans into delirium.
Chelsea deservedly restored parity through Cesar Azpilicueta's delightful flick late in the first half.
Marcos Alonso put the Blues ahead in extra time before Kepa Arrizabalaga saved Hardie's tame spot-kick.
More to follow.