Both sides went into this FA Cup quarter-final having suffered disappointing defeats in their respective European matches. Chelsea were undone by a Steaua Bucharest penalty in the first leg of their Europa League tie, whilst Manchester United were dumped out of the Champions League by Real Madrid.
Man United had two extra days to recover from their game, and their freshness showed as Javier Hernandez caught Petr Cech off his line when he headed home an excellent Michael Carrick cross inside five minutes.
The home side doubled their lead on 12 minutes when a Wayne Rooney free kick bypassed everybody in the area before curling inside the far post.
It looked like game over as Chelsea struggled to find their rhythm and although they grew stronger as half-time approached, they were still suffering from the same lack of sparkle that saw them stifled in Romania.
Rafa Benitez waited until seven minutes after the break before making a double substitution, replacing Frank Lampard and Victor Moses with John Obi Mikel and Eden Hazard. As the Blues increased the pressure on United, a breakthrough became inevitable; it was substitute Hazard who provided it.
A wonderful strike from the edge of the box floated beautifully across the face of goal before curling in at the far post. Ten minutes later Ramires levelled the scores and despite the late introduction of Fernando Torres it ended 2-2, forcing the FA to find some way of scheduling a replay at Stamford Bridge.
Below are the ratings for Chelsea's starting 11 plus two substitutes on Sunday. Every player starts on 5/10 and points are awarded or deducted based on attitude, work-rate and contribution to the game. A goal scored by a defender is weighted higher than one scored by a striker, and red cards and missed penalties get an automatic one-point deduction.
Petr Cech: 5.5/10
Cech was caught off his line for the first goal, and whilst there was little he could have done about the second it was his poor decision making in the opening minutes that forced Chelsea to chase the game. He made an excellent double save from Wayne Rooney and David Luiz to keep the Blues' hopes alive.
Cech's passing accuracy was the lowest of any Chelsea player at 57 percent, and as he had little to do in the second half, his rating is based on his performance in the first 45 minutes.
Cesar Azpilicueta: 7/10
Azpilicueta made three interceptions and blocked a shot on goal as United attacked on the counter. His passing was 82 percent accurate, and although his crossing still needs work his overall performance was good.
He lost 0.5 from his score for a yellow card picked up in the first half.
Gary Cahill: 6.5/10
Cahill is a good centre-half when paired with the experienced John Terry. On the occasions where he has partnered either Branislav Ivanovic or David Luiz, he has lacked focus and caused problems for his teammates. Despite a shaky first 15 minutes he recovered well to make three effective clearances and two interceptions.
He was 90 percent accurate with his passing, and he had one shot off target.
David Luiz: 7.5/10
Social media was set alight with the consternation of Chelsea fans when Rafa Benitez decided to start David Luiz at centre-half ahead of John Terry. Luiz showed earlier in the season that his style of play is better-suited to a defensive midfield role as it gives him room to roam without leaving Cech exposed.
Despite forcing his 'keeper to make a point-blank save when he headed Rooney's rebound towards his own goal, Luiz was less of a liability than he has been of late. He made seven effective clearances, four interceptions and two tackles as well as completing 85 percent of his passes and having one shot on target.
Ashley Cole: 7/10
Cole blocked one shot and made two effective clearances in a game where his primary role was to feed the attacking trio from the left wing. His passing accuracy was 92 percent, and he played three accurate long balls.
Frank Lampard: 6.5/10
Lampard had a passing accuracy of 81 percent and made one key pass. He made two tackles and one interception as well as having one shot on target before being substituted for John Obi Mikel on 52 minutes.
Ramires made four accurate long passes with an overall accuracy of 87 percent in a game that saw him really step up in the second half. He got the equaliser to take the tie to a replay as well as making four tackles and six interceptions.
With five successful dribbles and six key passes alongside one tackle and three interceptions, Oscar was in charge of the Chelsea midfield. He found Ramires with a wonderful through-ball for the equaliser, and his overall work-rate was superb.
Juan Mata: 8/10
Mata set up substitute Eden Hazard for Chelsea's first goal and had a passing accuracy of 88 percent. Unusually for the midfield maestro he got involved defensively as well, making three tackles and two interceptions. He had two shots saved, one of which David De Gea had to be at full stretch to toe-poke away.
Victor Moses: 6.5/10
Moses had two shots at goal, neither of which were on target, and eight of his 10 passes found their intended target. He made one tackle and one interception before being substituted for Eden Hazard after 52 minutes.
Demba Ba: 7/10
Ba had three shots, forcing De Gea to make a save from one of them.
He found himself in some good positions but was unable to make the goalscoring impact. Fernando Torres replaced him with 13 minutes remaining.
Eden Hazard: 8/10
Hazard entered the match with 40 minutes to go, replacing the ineffective Victor Moses. His impact was immediate as he gave Chelsea a lifeline with a goal seven minutes after joining the fray. He had a total of three shots on target and a passing accuracy of 83 percent but loses 0.5 from his overall score for picking up a yellow card.
John Obi Mikel: 7/10
Mikel made a tackle, an interception and a clearance in the 40 minutes he was on the pitch and had a passing accuracy of 89 percent. The stability he brought to the midfield showed that it makes far more sense to start him with Lampard or Ramires to give a solid link between the defence and attack.