Ten-man Millwall shocked champions of England Leicester with a last-gasp 1-0 win at the Den on Saturday to progress to the quarter-finals of the FA Cup.
The Sky Bet League One side had already knocked out Premier League clubs Bournemouth and Watford on their way to the fifth round and added another top-flight scalp to their collection thanks to Shaun Cummings' 90th-minute winner.
Jake Cooper's 52nd-minute sending off for a second bookable offence had left the south London side with a huge task on their hands but they were inspired by the challenge, and heaped more pressure on under-fire Leicester manager Claudio Ranieri.
The Italian had made 10 changes from last weekend's Premier League defeat at Swansea - their fifth league loss in a row - including handing January loan signing Molla Wague a debut, and the visitors were by far the stronger side for much of the first half.
Impressive Demarai Gray had the pick of their chances on 10 minutes when he made room for himself on the left-hand side of the box and curled a right-foot strike wide of the far post.
Millwall 'keeper Jordan Archer pulled off a smart stop to keep out Shinji Okazaki on the quarter-hour mark and Byron Webster produced a last-ditch block to deny Ahmed Musa on the rebound.
Musa - who had earlier sliced a long-range effort out for a throw-in - then arrowed a right-foot effort narrowly wide before miscuing from an Okazaki lay-off on 20 minutes as Leicester put on the pressure.
The Nigeria international also fired over the bar five minutes before the interval but it was the home side which finished the half on top.
Steve Morison headed a free-kick over the bar off Yohan Benalouane, Calum Butcher nodded the resulting corner straight at Ron-Robert Zieler before Webster fired a shot at the Leicester keeper from another set-piece which sparked a goal-mouth scuffle when the German spilled the ball.
Millwall's Cooper was booked by referee Craig Pawson for going in too hard on the shot-stopper - and paid for that foul just five minutes after the re-start when he clattered Musa and received his second yellow card.
Down to 10 men, Millwall actually enjoyed some of their best moments of the match, with a Morison cross just evading Fred Onyedinma, before the striker and Shaun Williams tried their luck from range.
In a bid to turn the tide back in his team's favour, Ranieri sent on Marc Albrighton and Jamie Vardy, and the England international dragged a low, left-foot shot wide from the edge of the area with 13 minutes to play.
Okazaki then wasted a glorious opportunity to win the tie from six-yards out after Albrighton's cross had found its way through to him in space, but the striker shot at Archer, who did well to stay on his feet and keep it out.
Archer pulled off another smart stop to palm away Okazaki's deflected cross on 85 minutes after Millwall had handball appeals against Benalouane in the Leicester box rightly waved away.
Millwall began to control possession in the final five minutes, but then got the break they'd been waiting for when Onyedinma's ball forward found substitute Lee Gregory who played in on-rushing right-back Cummings to coolly slot in.
The home side held off an injury-time charge from last season's Premier League winners and claimed a remarkable FA Cup upset to reach the last-eight.