We look back at the Portuguese forward's finest moments on the hallowed home turf, detailing his "firsts" for the club as well as a certain incredible free kick.
Feel free to add your memories of Cristiano in the comments below.
Cristiano Ronaldo asked for No. 28, but Sir Alex Ferguson told him he was to assume the shirt recently vacated by the Real Madrid-bound Beckham.
Talk about ramping up the pressure. Ronaldo simply admitted later he was too scared to argue about the decision.
Cristiano Ronaldo's home debut came in August 2003 as he was subbed on during a clash with local rivals Bolton Wanderers.
With the side 1-0 up at the time but struggling to finish the Trotters off, the Portuguese prodigy provided some spark and ingenuity. He dazzled with his vast array of skills and step-overs, and the Red Devils ran out 4-0 victors.
Sir Alex Ferguson was more than impressed.
Manchester United overcame a stubborn Portsmouth side 3-0 at Old Trafford in late 2003, and the game marked Cristiano Ronaldo's first goal for the club.
It was a tight affair—much like the Bolton Wanderers match—until Ronaldo's introduction in the final 10 minutes, when he scored and assisted to help seal the result.
In 2008, Cristiano Ronaldo finally bagged his first hat-trick in a Manchester United shirt as they demolished Newcastle United 6-0.
The relief on his face was plain to see as the feat was a long time coming, and this was around the time he began to strike the ball so sweetly every time.
If you were to pick out a single free kick in Cristiano Ronaldo's career and label it "the one that opened our eyes," it would be this one.
1-0 up against Portsmouth just weeks after scoring the hat-trick against Newcastle United, the Portuguese forward smashes this one into the net from distance.
The technique, the movement. David James just shrugs his shoulders.
As stated, this list compiles a few of Cristiano Ronaldo's most eye-popping moments on the turf of Old Trafford. But some of his great exploits have been carried out on away trips, so here's a few to treasure here:
—The tear-filled, emotional celebration of the win following the penalty shootout.
—The opener against Millwall in his first trophy win
—The multitude of awards won, both individually and for the team, throughout his career.