Nottingham Forest produced a fantastic performance to dump Emirates FA Cup holders Arsenal out of the competition with a 4-2 win at The City Ground.
An enthralling contest saw Eric Lichaj hit a superb brace, with penalties from Ben Brereton and Kieran Dowell helping to send The Reds through to the fourth round.
Per Mertesacker had brought Arsenal level in the first half and Danny Welbeck's goal looked to get The Gunners back into the game but Forest, who had Joe Worrall sent off late on, sealed a memorable victory.
Forest started confidently against the holders, looking compact in defence but also a threat on the break. The first opening came on six minutes as Ben Brereton latched onto a loose pass in the Arsenal defence, but his left-footed shot was well held by David Ospina.
The visitors had the majority of possession in the opening exchanges and Theo Walcott had their first sight of goal, receiving Alex Iwobi's pass in the penalty area but scuffing his shot straight at Jordan Smith.
The Reds came agonisingly close to taking the lead on 18 minutes as Ospina was called into making a superb stop from Matty Cash. A counter-attack led by Zach Clough led to the ball finding its way across the area to Cash whose low drive was tipped around the post by the Colombian's fingertips.
Forest kept the pressure on The Gunners' goal and took the lead on 20 minutes through Lichaj. Dowell had done well to initially win a free kick on the byline, then the loanee delivered a dangerous free kick straight at Ospina, and the full back dived in front of the keeper to head into the roof of the net.
But the lead didn't last long as Arsenal captain Mertesacker equalised four minutes later. Fellow centre back Rob Holding rose highest at a corner to head against the post and the experienced German was on hand to prod home to bring the Premier League side level.
It was a great cup tie at The City Ground and were it not for another fine Ospina save, Brereton could have restored The Reds' lead. The teenager weaved his way into the box and his low left-footed strike was stopped by a firm hand from the Arsenal keeper.
An enthralling first half had one final moment to savour as Lichaj put The Reds 2-1 up. A delivery into the Arsenal area was only half-cleared to the edge of the box where the American full back controlled the ball on his chest and sent a sumptuous volley dipping into the top corner of the net.
At the start of the second half, Arsenal came out with intent and kept Forest camped in their own half without creating anything clear-cut. The Reds looked to utilise the outlet of Brereton, who was in a fierce battle with Holding and Mertesacker.
Just after the hour-mark it was Forest who carved out an opportunity, with substitute Tyler Walker chasing a seemingly lost ball down the left to deliver into the middle for Brereton whose effort deflected past Ospina's post.
The vital third goal did arrive and Brereton was the one to get it from the penalty spot. The tireless endeavour of Matty Cash saw him steal the ball from Holding in the area who then brought him down. Brereton stepped up to send Ospina the wrong way and get the goal that his performance deserved.
The Reds still had to keep things tight at the other end as substitute Eddie Nketiah had a sight of goal. The ball was flicked through by Welbeck and the youngster took a touch before being denied by a fine save by the onrushing Smith.
However, on 79 a defensive mix-up allowed Arsenal a way back into the game. Smith seemed to have claimed the ball on the edge of the box, but the ball was loose and Welbeck prodded the ball goalwards and it trickled over the line and into the unguarded net.
This belting cup tie took another twist with five minutes to go as Armand Traore's superb run saw him go around two Arsenal defenders before Mathieu Debuchy hauled him down inside the area.
Dowell assumed penalty taking duties and, despite slipping when kicking it, sent the ball high into Ospina's net, cueing a raft of protests from the Arsenal players who believed he kicked the ball twice.
The action didn't end there though as a crunching tackle by Worrall in the middle of the park saw the Forest defender shown a red card with just minutes remaining but ultimately it didn't matter as Forest sent the holders out of the competition on a memorable afternoon on Trentside.
Forest: Smith, Lichaj, Mancienne (c), Worrall, Traore, Cash (McKay 87'), Vaughan, Osborn, Clough (Walker 56'), Dowell (Mills 90'), Brereton
Unused subs: Henderson, Bouchalakis, Cummings, Vellios
Goals: Lichaj 20', 44', Brereton pen 64', Dowell pen 86'
Booking: Worrall 84'
Red card: Worrall 89'
Arsenal: Ospina, Debuchy (Akpom 87'), Mertesacker (c), Holding, Maitland-Niles, Elneny, Willock (Nketiah 65') Walcott, Iwobi, Nelson, Welbeck
Unused subs: Macey, Chambers, Reine-Adelaide, Dasilva, Osei-Tutu
Goals: Mertesacker 24', Welbeck 79'
Bookings: Debuchy 84', Ospina 85', Mertesacker 86', Welbeck 86'
Referee: Jon Moss