While unfortunate, the steward (luckily) was okay and, after the Portuguese forward had checked on her, he handed his shirt over after the game. Scant consultation perhaps, but certainly quite the day at the office.
Now, footage has emerged after images had shown Ronaldo reacting to the incident.
Indeed, a YouTube video shows the 36-year-old taking what appears to be a free-kick (which may actually be reasonably unsurprising given his efforts on that front of late) which sailed over the bar, hitting the unsuspecting security guard in the back of the head.
Thankfully, the poor soul emerged from it in fine fettle.
United, however, did not.
After Ronaldo had put them ahead in the first-half following a wonderful assist from Bruno Fernandes, Aaron Wan-Bissaka’s early red card made the task so much more difficult, with the home side scoring twice after the break to secure a famous win.
For Ronaldo, it was quite the eventful evening.
“He [Ronaldo] should have had a penalty and it should have been a sending off the other way,” he said (via The Daily Mirror).
“But he probably didn’t give it as he’d have had to send him off and that’s sometimes what you get with young refs.”
Taken off for Jesse Lingard in the second-half, it was the England international’s careless backpass that allowed Theoson Siebatcheu to slot home in the dying embers.
While not a complete disaster, Ronaldo’s return to Champions League action for United did not exactly go to plan. Before or after his time on the pitch.