For the most ludicrously controversial moment of the entire European season, you have to look back to the second leg of the Champions League second round.
With Manchester United a goal up against Real Madrid, Portuguese winger Nani was shown a straight red card for a high boot—Turkish referee Cuneyt Cakir citing dangerous play—and within moments the Red Devils' European Cup dream had all but died as they conceded two quick-fire goals to be knocked out of this season's competition.
It was a decision that many believe changed the entire course of the tie, handing the initiative to Real Madrid, who utilised their extra man and got the result they required to proceed to the quarter-final.
But what if it had never happened? What if the official saw the challenge and deemed it worthy of only a yellow card. How would Manchester United's season then have panned out?
Let's take a prophetic look, at how things may have worked out.
At the time of Nani's ejection, United held a 1-0 lead.
However, Real Madrid were certainly the side in the ascendancy. The Spanish giants were dominating possession and forcing United to defend a 20-yard stretch outside their penalty box. Robin van Persie was becoming isolated, and United counter attacks were becoming less frequent.
With Mourinho making clever substitutions, such as Croatian playmaker Luka Modric, who came on to find space in between the lines to terrific effect, there was simply no guarantee that United would hold on to their lead even with 11 men.
Throw in the fact that the likes of Mesut Ozil and Gonzalo Higuain were starting to have a bigger impact on proceedings, and with Cristiano Ronaldo lurking, you simply can't definitively state that Madrid wouldn't have scored.
As such, although Nani may have remained, and whilst it may have taken that bit longer to get the job done (perhaps extra-time), Real Madrid would still have done the required job to make their way into the quarter-final draw, as they continue their quest for "La Decima"—Their 10th European Cup.
For United, the season would then have continued as it has in reality: Without the Champions League to offer the potential for distraction, their dominant push towards the English league title would continue, and they would remain handsomely atop the Premier League.
On the other hand, with Nani remaining on the field of play, United continue their game plan of soaking up pressure and hitting Madrid on the break.
The Portuguese remains an outlet on the counter-attack and in tandem with Danny Welbeck, Robin van Persie and the energetic Tom Cleverley, United continue to have options whenever they advance.
Throw into the mix that the centre of the pitch remains crowded, with Welbeck continuing to do a good job of hustling Xabi Alonso, and Madrid struggle to find any kind of fluency in the final third.
Therefore, they remain unable to break down a resolute United rearguard, who make the tie safe in the 86th minute, when a swift breakaway leaves Van Persie free to tap in from six yards.
United book their place in the quarter-finals, and confidence is unquestionably soaring.
But how does that impact on the rest of their season?
Having seen off Real Madrid in the second round, United are installed by bookmakers as second favourites (behind Barcelona) for the trophy and get a certain degree of fortune in drawing Galatasaray— arguably the weakest of the eight remaining sides—as their quarter-final opponents
With Old Trafford in expectant mood and the United players brimming with confidence after the success against Madrid, they make an extremely quick start against the Turkish club, taking a two-goal lead inside the first 25 minutes at Old Trafford, with Van Persie and a restored Wayne Rooney scoring the goals.
Rooney adds a third before half-time, and United are cruising against Fatih Terim's side, who appear too open through midfield, with Wesley Sneijder's integration and his role in the side still very much open for discussion.
However, the second half sees United become sloppy, and rather than completely killing the tie, Terim's side—who emerged for the second period with Sneijder having been substituted—make the most of their opportunity and leave Old Trafford with an away goal to their name, Buruk Yilmaz heading home from an Albert Riera cross.
Nevertheless, United leave complacency at home during the second leg, and despite a hostile reception at the Turk Telekom Arena, they battle hard to earn a 1-1 draw, Van Persie giving them a second-half equaliser after an early goal from Didier Drogba.
Thus, a place in the last four is assured. But what about their league campaign?
Despite the extra European commitments, Manchester United's relentless charge towards a 20th English league crown continues.
Sir Alex Ferguson continues to utilise his squad to good effect, and the Red Devils head into their final five games of the season with an astonishing 13 point lead over reigning champions Manchester City, whose inconsistency has allowed United to run away with the title.