Stat Attack: All you need to know about Chelsea 2-1 Plymouth (aet)
Chelsea needed an extra-time goal from Marcos Alonso to beat League One Plymouth Argyle 2-1 and avoid an FA Cup fourth-round shock.
Argyle stunned Stamford Bridge in the eighth minute, going in front when Macaulay Gillesphey found space in the box to nod Jordan Houghton's free-kick past Kepa Arrizabalaga.
Mateo Kovacic rattled the woodwork twice before the Blues equalised shortly before half-time when Cesar Azpilicueta flicked Mason Mount's low cross in after a slick team move, but Chelsea were unable to secure victory inside 90 minutes, forcing extra time.
The Blues finally went ahead in first-half extra time, courtesy of another Spanish defender, with Alonso popping up to steer Kai Havertz's cut-back into the bottom corner.
Ryan Hardie had a golden chance to take the game to penalties with a spot-kick in the 118th minute, but Kepa guessed the right way and saved low down to win the tie for the hosts.
Despite the defeat, Plymouth manager Steven Schumacher, speaking to the BBC, revealed his pride at how his players had performed.
He said: "We're really proud. We knew it was going to be a really tough day. We wanted to make our fans proud and I think we did that.
"A lot of the credit this week has to go to Keith Downing, who is a really good out-of-possession coach. We had to be organised and the back three had to defend their goal really, really well.
"I think both goals were from their full-backs, but I can't be too disappointed with our players. I think their legs went at the end.
"Ryan Hardie is devastated. He normally strikes the penalties better than that. He'll be disappointed but he can't dwell on it too long.
"We're moving well and going in the right direction as a club. It's a great club to work at. That's the aim — to get to the Championship."
Did you know?
Since his FA Cup debut in January 2013, no player has made more appearances in the competition than Azpilicueta (35 — level with Olivier Giroud).
Azpilicueta's strike today against Plymouth was his first-ever FA Cup goal in 35 outings in the tournament.
Mount's assist for the opening goal was his 10th assist in all competitions this season. The midfielder also has seven goals, meaning he has already matched his total goal contributions (17) from the whole of last season in 22 fewer appearances.
Havertz's assist for the winning goal means he now has more direct contributions to a goal (five — three goals, two assists) in cup competitions than he does in the Premier League (four — two goals, two assists) for Chelsea this season.