Millwall narrowly avoided being knocked out by the side currently bottom of League One
Substitute Aiden O'Brien hit an 89th-minute winner as Championship Millwall avoided a shock against Plymouth to reach the Carabao Cup third round.
Millwall twice fell behind, Shane Williams' penalty cancelling out Jamie Ness' opener before Freddie Ladapo restored the League One side's lead.
Millwall boss Neil Harris made all his substitutes and was rewarded when Lee Gregory equalised after 83 minutes.
The Lions chased a winner and O'Brien was on hand to turn home late on.
It was cruel on Plymouth, whose spirited performance belied their current status as League One's bottom side.
Featuring seven changes from their 1-0 loss at Rotherham at the weekend, Millwall took some time to get going with Ben Amos called into action to deny Ness.
However, they grew into the game and responded when they needed to before decisively finishing the stronger.
