Sir Alex Ferguson opted for 10 changes to the team that defeated the Blues in their last league match on Sunday. Roberto Di Matteo, on the other hand, made six changes to the Chelsea team from Sunday.
Manchester United drew first blood in a reasonably even first half, when Anderson dispossessed Oriol Romeu deep in Chelsea territory. Ryan Giggs was at hand on the edge of the penalty area to pass the ball past Petr Cech and into the net.
Most of United's attacking threat came from the interchanging of their midfield players. Darren Fletcher and Ryan Giggs were quite content to sit relatively deep, while the trio of Anderson, Danny Welbeck and Nani kept swapping positions around the Chelsea midfield duo of Romeu and John Obi Mikel.
For Chelsea, both Romeu and Mikel received first-half cautions as they found it difficult to cope with United's movement and composure on the ball. The low point was the mistake that ultimately led to Giggs' opener.
On the other hand, Victor Moses had a very lively first half as he constantly troubled United's left-back, Alex Büttner. This matchup gave Chelsea a way back into the game when Büttner tripped Moses in the box for a clear penalty. David Luiz stepped up to take the penalty and equalized for the Blues.
However, it was Luiz who was responsible for the mistake that led to Manchester United retaking the lead on the stroke of half-time. He lost possession near the halfway line. United took advantage by moving the ball quickly to Anderson, who curled a wonderful pass into Javier Hernandez's path. The Mexican predator made no mistake as he scored his sixth goal against Chelsea in nine appearances.
Büttner's horrendous game was summed up when he had to taken off at half-time for an injury. Nick Powell came on for Büttner, resulting in a Manchester United reorganization at the back. Darren Fletcher went into the right-back position while Rafael played the second half as the left-back.
The second half saw Chelsea equalize yet again through Gary Cahill's header from a Juan Mata corner. However, Manchester United hit back within seven minutes with the goal of the game. A move that began with Powell passing to Hernandez resulted in Anderson and Nani exchanging a one-two in the Chelsea box. Anderson's return pass found Nani's run into the penalty area and the Portuguese winger scored Manchester United's third with a neat, dinked finish over Petr Cech.
From there on in, the game settled into a pattern of Chelsea trying to press and find the equalizer, with United trying to catch them on the counter attack. Chelsea carved out a couple of good chances in this phase for César Azpilicueta, who kept ghosting behind Rafael from the Chelsea right. In a bid to rescue the game, Roberto Di Matteo sent on both Eden Hazard and Oscar in place of Lucas Piazon and Oriol Romeu, respectively.
Just as it seemed that United would hold on to their slim one-goal advantage, Scott Wootton bundled over Ramirez in the penalty area in the fourth minute of stoppage time. Eden Hazard stepped up to the plate and confidently scored the penalty to send the game into extra time.
The first period of extra time saw an end-to-end start as both teams looked to score the goal to win the tie. A pivotal moment came on 97 minutes when Scott Wootton's mistake allowed Daniel Sturridge to score Chelsea's fourth goal. It was a bitter blow for Manchester United's reserve team player of the season from last season.
In response to going behind, Sir Alex Ferguson brought on Federico Macheda instead of Danny Welbeck, although the decision was probably taken with one eye on the weekend's upcoming game against Arsenal.
United's response was predictable as they threw men forward in search of the equalizer. However, this left them vulnerable to Chelsea counter attacks. One such Chelsea counter attack saw Ramirez score Chelsea's fifth and put the tie beyond United. Giggs' penalty in the last minute of extra time came too little, too late for the Red Devils as Chelsea emerged winners by a margin of five goals to four.
From a United perspective, Sir Alex will feel disappointed that United could not hang on to their 3-2 lead despite being second away from a famous victory. The fact that the Red Devils scored four and yet could not win the tie was also an uncomfortable statistic, especially for the defence.
However, there were positives from the game too. United looked good in attack once again, with Chicharito, Anderson and Giggs shining in their roles. Nani, as is his wont, looked good for large parts of the match.
The match also provided valuable experience for the youngsters in the team. Both Ryan Tunnicliffe and Nick Powell showed tantalizing glimpses of their potential. Both Michael Keane and Scott Wootton performed reasonably well for ninety minutes.
While it is true that a young central defender made the mistakes which cost United the tie, he will be a stronger character and player for having made them and for the way he tried to help his team recover from the deficit.
Finally, it was rather indicative of the strength of this obviously second string Manchester United side that Chelsea needed to bring on their big hitters to secure a victory and that it took them until the last minute of extra time to earn the said victory. The defeat will be so much less bitter if the rigors of the game cause Chelsea to drop points away to Swansea City on the weekend.
Chelsea: Cech; Azpilicueta, Cahill, Luiz, Bertrand; Mikel (Ramirez 45'), Romeu (Oscar 72'); Moses, Mata, Piazon (Hazard 55'); Sturridge
Manchester United: Lindegaard; Rafael, Michael Keane, Scott Wootton, Alex Büttner (Powell 45'); Fletcher, Giggs; Nani, Anderson (Tunnicliffe 81'), Welbeck (Macheda 97'); Hernandez
Chelsea: Luiz (pen.) 31', Cahill 52', Hazard (pen.) 90'+4', Sturridge 97', Ramires 116'
Manchester United: Giggs 22', Hernandez 43', Nani 59', Giggs (pen.) 120'