Ronaldo scored twice on his return to Old Trafford to help United run out 4-1 winners.
The 36-year-old is a physical phenomenon and nothing proved it more than his second goal on Saturday.
Luke Shaw slotted a ball through to Ronaldo, who took it in his stride before firing it between the legs of Freddie Woodman.
Ronaldo battled off challenges from Javier Manquillo and Isaac Hayden, who were left in the dust.
BBC Sport have now confirmed the five-time Ballon d'Or winner managed to reach 32.5kmph, which is roughly 20.2mph.
We're going to remind you that he's 36-years-old once again. Closer to 40 than 30. It defies the laws of nature.
:bar_chart: During the run he made for his 2nd goal, Cristiano Ronaldo hit a top speed of 20.2mph (32.5kmph). [BBC]- UtdDistrict (@UtdDistrict) September 11, 2021
Still got it :zap: pic.twitter.com/yLifPuneEH
Fans inside the Theatre of Dreams were buzzing to see Ronaldo in his first game since signing from Juventus.
He started up front and put United ahead after Mason Greenwood's shot was spilled by Woodman.
Newcastle did threaten to spoil the party however thanks to an equaliser from Manquillo on the counter.
Ronaldo fired back moments later before Bruno Fernandes' long-range effort put United out of sight.
Jesse Lingard scored his first goal of the season in added time to see the Red Devils move to the top of the Premier League.
Ronaldo was brought back onto the pitch for his post-match interview and was serenaded with 'Viva Ronaldo' chants.
He said: "It's unbelievable. When I started the game I was so nervous, I swear. Maybe it didn't show but I was.
"I didn't expect to do that, to score two goals. Maybe one but not two. Of course, I'm happy to score the goals, I won't deny that, but the most important thing is the team.
"I belong to Manchester United. I arrived here at 18-years-old, they treated me unbelievably and this is why I came back. I'm so proud to be here and I want to win.
"Everyone knows that the football here in England is different than any part of the world. I've played everywhere and, to be honest, England is the most special one...
"This crowd is unbelievable and I'm going to give everything to make them proud of me. I didn't expect they would sing all game my name. The reception is incredible, but I'm here to win games, to help the team and get the club back where they deserve.
"Manchester United need to be where they deserve. It's to win to build a team, build a club and build a mentality this is what we are looking for."
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