Wolverhampton Wanderers produced an outstanding second-half performance to overpower Manchester United and reach their first FA Cup semi-final for 21 years on an atmospheric night at Molineux.
Nuno Espirito Santo's side, in their first quarter-final since 2003, fully deserved their victory as United produced their worst performance under the interim management of Ole Gunnar Solskjaer.
United goalkeeper Sergio Romero, in for David de Gea, had kept United level with brilliant saves from Diogo Jota and Raul Jimenez either side of the interval, before the Mexican striker swivelled in the area to finally give Wolves the reward their domination merited with 20 minutes remaining.
Wolves were rampant and it was no surprise when the dangerous Jota doubled their lead six minutes later, shrugging off United's Luke Shaw on the break before shooting low past the exposed Romero.
United defender Victor Lindelof was shown a red card by referee Martin Atkinson for a touchline challenge on Jota, but it was downgraded it to yellow after a VAR review and, even though Marcus Rashford pulled one back in stoppage time, Wolves were worthy winners.
Sergio Aguero's controversial late winner ensured Manchester City dramatically kept their quadruple bid on track as they came from two goals down to beat Swansea and reach the FA Cup semi-finals.
Substitute Aguero beat Swansea keeper Kristoffer Nordfeldt with a diving header off Bernardo Silva's low cross at the end of a superb move in the 88th minute.
Replays showed the Argentina striker was marginally offside but the video assistant review system was not in use at the Liberty Stadium, despite having been used in City's third and fourth-round ties at their Etihad Stadium home.
City had levelled in contentious circumstances too when Cameron Carter-Vickers was judged to have tripped replacement Raheem Sterling in the area and Aguero's penalty hit the post before rebounding in off Nordfeldt for an own goal.
Defeat was harsh on the impressive hosts, who led 2-0 inside 30 minutes through Matt Grimes' penalty and Bersant Celina's spectacular second.
The former City player, who was mocked for an extraordinary penalty miss against West Brom on Wednesday, curled a sumptuous first-time effort beyond Ederson at the end of a tremendous, flowing move.
City fielded a strong side but needed Sterling and Aguero to come off the bench to shake them out of their fatigue, the latter setting up Bernardo for the visitors' opener, which sparked their thrilling comeback in the last half hour.