The debate over Lionel Messi and Cristiano Ronaldo reared its head again this summer after the pair wrapped up blockbuster transfers.
Messi completed a shocking departure from Barcelona to join French giants Paris Saint-Germain, while Ronaldo sealed an emotional return back to Manchester United.
But it had seemed that Ronaldo was on the cusp of joining United's bitter rivals Manchester City until Ole Gunnar Solskjaer's late swoop.
However, in the space of seemingly just a few hours, Ronaldo's controversial move to the Etihad fell away and a second spell at United was confirmed.
Since then, details have emerged of the lengths that the Old Trafford hierarchy and his former United team-mates went to in order to wrap up a deal for the Portuguese star.
Of those who intervened, perhaps none were as pivotal as Sir Alex Ferguson.
In fact, Ronaldo even dedicated his return to Old Trafford to his old boss in an emotional Instagram post after his return was confirmed.
"I’m right here! I’m back where I belong! Let’s make it happen once again!" said Ronaldo at the end of his post.
"PS - Sir Alex, this one is for you…"
Ferguson was the man responsible for bringing Ronaldo to Old Trafford initially back in 2003.
The United chief acted as a mentor for the teenage star as he adapted to life in England - eventually evolving into a global star before his departure in a then-record £80m dream transfer to Real Madrid.
But, even after Ronaldo's departure, the pair have remained in close contact, with their relationship as strong as ever.
The 36-year-old is said to lean heavily on Ferguson for advice even to this day - something which helped United steal a march on their rivals.
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Perhaps then, it's no surprise who Ferguson favours when comparing Ronaldo and Messi.
"People say who is the best player in the world? And plenty of people quite rightly say Messi - you can't dispute that opinion," explained Ferguson back in 2015.
"But Ronaldo could play for Millwall, Queens Park Rangers, Doncaster Rovers… anyone, and score a hat-trick in a game. I'm not sure Messi could do it.
"Ronaldo's got two feet, he's quick, great in the air, he's brave - Messi's brave, of course. I think Messi's a Barcelona player."
Even with that ringing endorsement, it's likely that United wouldn't have budged from their bid to recapture Ronaldo were Messi still on the market.
The pair dominated La Liga for years during their spells at Barcelona and Real Madrid, often going toe-to-toe for both team glory and solo accolades.
In terms of trophies, Messi's 10 La Liga titles with Barcelona trumps Ronaldo's tally of seven - however, Ronaldo has tasted domestic success in England, Spain and Italy compared to just Spain for Messi.
However, Ronaldo comes out on top in Europe - with his tally of five Champions League titles eclipsing the four won by Messi.
It's that championship pedigree and winning mentality that convinced United to hijack Ronaldo's potential switch to City.
Solskjaer will be hoping that Ronaldo can help them challenge for trophies again - even if his arrival is likely to ramp up the pressure on the Old Trafford boss.
The Norwegian, who played alongside the Portuguese star for four years, knows the Old Trafford hierarchy will expect a return on a summer of heavy investment.
"You run out of words to describe Cristiano. I have no doubt that he will continue to impress us all and his experience will be so vital for the younger players in the squad."
He'll be hoping that Ronaldo can still deliver against teams of a higher calibre than the ones reeled off by Ferguson if he and United are to challenge for honours as expected this season.
If Ronaldo's international exploits are anything to go by, it won't be a problem.
The Portuguese icon broke Ali Daei's long-standing international goal-scoring record with a brace against the Republic of Ireland on Wednesday night, making it 111 goals for Portugal.
You wouldn't bet against Ronaldo breaking more records now he's back in Manchester.
