After losing to Steaua Bucharest on Wednesday, Chelsea found themselves trailing 2-0 to Manchester United after just 11 minutes on Sunday. At the end of the first half, it looked like the Blues' season was all but over.
The second 45 minutes brought out a very different Chelsea side. Rafael Benitez brought on Eden Hazard and John Obi Mikel in the 52nd minute, and the game changed dramatically. The Blues dominated and were rewarded with goals from Hazard and Ramires.
Chelsea forced a quarter-final replay with United, but they will certainly be kicking themselves for not winning the match. On the other hand, Sir Alex Ferguson will be angry at his side's lethargic second-half display.
Here are four things we learned or were reinforced by Chelsea's performance at Old Trafford.
In 133 appearances for Chelsea, Ramires has 22 goals and 14 assists. While those stats aren't bad for a midfielder, they aren't great either.
One thing that Ramires does very well, however, is score in big games. Last season, the Brazilian got 12 goals and eight assists. He scored against Liverpool in the FA Cup final, Barcelona in the Champions League semi-final and Valencia in Chelsea's final group stage match.
This season, Ramires has just eight goals and six assists in 45 appearances. Out of those eight goals, three have come against Manchester United.
Ramires' goal at Old Trafford on Sunday has kept Chelsea in the FA Cup and given them lots of hope of progressing to the competition's semifinal.
The 25-year-old may not score too many goals, but he can be invaluable in Chelsea's big games.
John Obi Mikel came off the bench in the 52nd minute and had a great second-half performance for Chelsea. The Nigerian stayed in defensive midfield, sitting right in front of David Luiz and Gary Cahill, and cut out many United attacks.
Mikel has been criticized in the past for being lazy and too defensive-minded, but his performance on Sunday certainly helped silence his critics. The 25-year-old kept Manchester United in their own half and allowed Chelsea's defenders to push up.
David Luiz was great when attacking but had a sub-par defensive performance against United. This season, the Brazilian has been pushed up to midfield many times, but Rafael Benitez started him at center-back in Sunday's contest.
Luiz was partially at fault when Rooney scored United's second goal and then made a reckless challenge on Rafael in the 56th minute. But while Luiz's defensive play was at times careless, he made multiple attacking runs and tested David de Gea several times.
Chelsea will want the former Benfica man to improve defensively, but there is no doubt that Luiz's offensive play helps the team.
In the 52nd minute, many Chelsea fans booed Benitez's decision to take off Frank Lampard in exchange for Obi Mikel. As it turned out, that substitution (including bringing on Eden Hazard for Victor Moses) ended up changing the game in favor of Chelsea.
As the Blues got back into the game, their fans started cheering. The supporters who had booed Benitez's substitution earlier in the game ended up looking foolish.
Many Chelsea fans will never forgive Benitez, but their booing only hurts the team as a whole. Hopefully Sunday's turnaround will show Blues' supporters that the Spaniard does know how to manage the club.