John Marquis scored his first goal in 17 months with a dramatic 89th-minute winner as Millwall knocked Premier League Aston Villa out of the FA Cup in sensational style at The Den.
Kenny Jackett's brave Lions had to battle back after going behind to Darren Bent's 22nd-minute effort and captain fantastic Danny Shittu cancelled out the opener just seven minutes later with his first-ever goal for the club.
The tie seemed to be heading towards a replay at Villa Park as the clock ticked down, but then Marquis struck right at the death to spark wild celebrations in front of a 15,007 crowd.
It was a moment to savour for the gutsy young striker who has endured a desperate stop-start time over the last season and a half with injury.
"I thought it was a terrific performance from the whole team tonight," beamed boss Jackett.
"I thought we deserved to win and I was so pleased for John Marquis that he got the wnning goal. He has been out for a long time and has worked so hard to get back to fitness."
Marquis was back in the starting line-up for the first time this season, whilst Liam Feeney returned from a hamstring injury, Karleigh Osborne started in central defence alongside Shittu and Mark Beevers moved to left-back.
From the opening minute, The Den faithful were in full voice but it was Villa who went close early on when Charles N'Zogbia's fierce effort flew narrowly wide.
James Henry saw his 13th-minute volley sail over the bar whilst Lions keeper David Forde was called into action on 21 minutes when he comfortably dealt with Andreas Weimann's flicked header from an N'Zogbia free-kick.
Villa broke the deadlock barely 60 seconds later when Feeney lost possession and Weimann's initial shot was parried by Forde but only straight into the path of Bent, whose mishit effort bobbled agonisingly into the back of the net.
Instead of grabbing the initiative, Villa were on the back foot immediately as The Lions roared back and Feeney was unlucky with a stinging shot straight into the hands of the grateful Shay Given in the Villa goal.
But the visitors, humbled by League Two Bradford City in the League Cup semi-final this week, showed their frailties defending set-pieces once again on 29 minutes.
Henry whipped over a great corner from the right and Shittu met the ball with a thumping header that gave Given no chance, raising the roof at The Den in the process.
Given was quick to punch an effort from Beevers clear and then stood rooted to the spot as Marquis sent a glancing header wide as Millwall sensed blood and powered forward in search of a second goal before half-time.
Both Adam Smith and Henry tried their luck from distance with efforts that tested Given, but the teams went in all-square at the break.
The second-half saw Villa enjoy a lot of possession, but they rarely tested Forde in the home goal with the exception of a low drive from Barry Bannan.
Man of the match Shittu made a couple of excellent blocks from the lively N'Zogbia but that was as far as chances went on the Villa front.
Millwall made their first change on 83 minutes when Dany N'Guessan replaced Andy Keogh and the added impetus up front paid off handsomely when six minutes later Millwall bagged the winner.
Smith's deep delivery from the right was met by Marquis whose initial header smacked the crossbar but he reacted quickest and stooped to head home the rebound from close range before disappearing under a pile of jubilant team-mates.
The six minutes of added on time might have felt like an eternity, but The Lions masterfully ran down the clock with the final whistle greeted by the loudest roar of the night as Jackett's men celebrated a famous win.
Forde, A.Smith, Shittu, Osborne, Beevers, Henry, Abdou, Trotter, Feeney, Keogh, Marquis. Subs: M.Taylor, Dunne, Wright, Batt, J.Smith, N'Guessan, Wilkinson.
Feeney (22mins), Beevers (80mins)
Shittu (27mins), Marquis (89mins)
Aston Villa: Given, Bennett, Vlaar, Clark, Lichaj, Delph (Bannan, 38mins), Westwood, Weimann, Lowton, N'Zogbia, Bent. Subs not used: Guzan, Ireland, Agbonlahor, Holman, Williams.
Bookings: Bennett (52mins), Bowery (81mins)
Scorer: Bent (22mins)
Att: 15,007 (away 1,609)