And he then had one of the best views in the house as the Portugal icon saved the Red Devils and gave them a last-gasp 2-1 victory over Villarreal in the Champions League.
It had looked like Bolt would witness a dismal result at the Theatre of Dreams when Paco Alcacer opened the scoring in the second half.
Ole Gunnar Solskjaer's team were playing nowhere near their potential and after three losses in their previous four games the pressure was cranking up.
But a wicked Alex Telles leveller and Ronaldo's late lash gave them a vital three points in Group F after their opening loss to Young Boys.
An Bolt is just glad to see the club legend back home where he belongs.
He told Man United before kick-off: "He helped to build the club and it was wonderful when he was here, the energy. So I'm happy he's back.
"I just saw Alex Ferguson inside and I thanked him for bringing Cristiano back, so I'm happy about it.
"I'm happy to be here, I haven't been back to Old Trafford in a while.
"So I'm just happy to be here in the stands with everybody to watch the game."
And before kick-off he even predicted Ronaldo would score - although he also felt Jadon Sancho would notch too.
Bolt is a huge fan of Ronaldo and earlier this year stated the 36-year-old, known for his fitness, could go on for another six years.
The eight-time Olympic gold medalist told the BBC: "He's on a different level, he is a machine.
"I think he will play until he's 42 because he will always be so fit and on a higher level to a lot of the younger players because of the work he puts in and the dedication he has."