Cristiano Ronaldo, a name that is sung all over Old Trafford, will be the enemy for the 90 minutes at the Bernabeu, and the following 90 - without counting extra time -- at Old Trafford.
Real Madrid and Manchester United are as big a couple of names as they come in the club game, and Ronaldo is one of the two greatest players in the world.
When the last 16 draw began at the UEFA headquarters in Switzerland, there was almost inevitability about the fact that Real Madrid would be drawn against Manchester United.
One thing that is always spelled out once the knockout stages of the Champions League begins is all ties are 180 minutes and not just the 90. True, but only up to a certain point.
The last time the two sides met, United were torn apart at the Bernabeu by the Galacticos of 2002/03. Then a truly amazing and one-for-the-memories game at Old Trafford was played in the second leg, which ended 4-3 in United's favor, with Ronaldo - the Brazilian legend - scoring a truly great hat-trick.
If this tie ends up being anything like the one ten years ago, then the fans are in for one hell of a time. United will be hoping lightning doesn't strike twice with the latest Ronaldo running riot.
As much as Real Madrid vs Manchester United is about 22 players on the field, with two great managers looking to outmanoeuvre one another on the touchline, there is a sense that the tie will be decided by Ronaldo.
The first leg will be the pointer towards what to expect when the two teams meet again at Old Trafford on March 5. If Real take a big lead, United are going to find it difficult, because Real will most likely score at Old Trafford.
Therein lies the most important aspect of any two-legged tie in Europe - the away goal. In Robin Van Persie, United have a player not too far off the stratospheric heights hit by Ronaldo and Messi. The prolific Dutchman is arguably the best purely central striker at the moment, and a man at the top of his game.
It's easy to imagine that the game will be a straight fight between Ronaldo, who warmed up perfectly with a hat-trick at the weekend, and Van Persie, who was not too bad either with a goal and an assist, and whoever ends up having the greater impact, will see his side progress. That is, to a point true.
But the great thing about two great teams facing each other is the smaller battles that will ensue across all sections of the field. Will Rafael be able to stop Ronaldo, or will Phil Jones be given the job of man-marking the Portuguese superstar.
Will Wayne Rooney give Xabi Alonso time on the ball to pick out those raking passes, or will Alonso himself be bothered by the vision and power of the United forward.
Can the ageing defensive duo of Rio Ferdinand and Nemanja Vidic - assuming the two start of course - quell the challenge of the likes of Karim Benzema, Mesut Ozil and Angel Di Maria, and will Michael Carrick be able to boss the middle of the park like he has done so often this season.
Real have been wayward this year, and have already lost the La Liga title to Barcelona, while United are marching towards their 20th Premier League crown with Manchester City floundering.
That might work in Real's favor, because, the Spanish side can turn pretty much their entire attention towards winning the Champions League.
At the end of the day, it all boils down to which team wants it more, because when you have so much quality on the pitch, anything is possible, even if all eyes will be on both teams' favorite son Ronaldo.
Team News and injuries: Real Madrid defender Rafael Varane, who was the man of the match in the Copa Del Rey first leg match against Barcelona, is a doubt through injury, with Iker Casillas sidelined with a broken thumb.
For United, Phil Jones and Jonny Evans face fitness tests after the duo were forced out of the game against Everton, while Paul Scholes has been ruled out through a knee injury.
Expected lineups: Real Madrid: Diego Lopez; Arbeloa, Ramos, Pepe, Marcelo; Alonso, Khedira; Di Maria, Ozil, Ronaldo; Benzema.
Manchester United: De Gea; Rafael, Ferdinand, Vidic, Evra; Welbeck, Welbeck, Carrick, Cleverley, Valencia; Rooney; Van Persie.
Prediction: 2-1 to Real Madrid
