Neil Harris has hailed his side's character after Millwall snatched a late 4-3 win at Bristol Rovers to cling onto the final Sky Bet League One play-off spot.
With Southend winning and Millwall having seen their 3-1 lead disappear, the Lions were set to finish seventh and miss out until Shaun Hutchinson's 85th-minute header at the Memorial Stadium.
But the goal secured Millwall sixth spot, and they'll now face Scunthorpe over two legs of the play-off semi-finals in a bid to make it to the final at Wembley.
"First of all, I just want to say how delighted I am for the boys," Harris told Millwall's official website. "We set out for a top-six finish this season and they've achieved that on top of going on a phenomenal FA Cup run, so full credit to the players for their efforts.
"Talk about twist and turns. It was a game that had everything from start to finish. Some of our play in the first half was brilliant and we deserved to be in front. We opened them up on several occasions and scored some high-quality goals.
"It's disappointing that they then came back to equalise but the lads have shown outstanding character to go on and win the game late on. It was a terrific header from Shaun and typified everything that was good about us today.
"We had players throwing themselves in front of shots all afternoon to preserve what we had and now it's about recovering for Thursday."