The phenomenal coming-of-age performances of Erling Haaland and Kylian Mbappe in the Champions League round of 16 matches has accelerated discussion of whether the era of Lionel Messi and Cristiano Ronaldo is already over.
That may well be premature, more reflective of the current malaise enveloping Barcelona and Juventus than any decline on the part of either Messi or Ronaldo.
Nevertheless, there is a growing sense that for the elder of the two, 36-year-old Ronaldo, time is running out.
He will go no futher than the Champions League round of 16 this year, following elimination by Porto, and it's unlikely he will be adding another Serie A title to his collection either.
He is caught in a strange limbo, and increasingly appears trapped between two eras: his stripped-down playing style doesn’t quite fit the fashion for high pressing and position rotation (a philosophy embraced, with mixed results so far, by Juventus manager Andrea Pirlo) and yet Ronaldo has 20 goals in 22 Serie A games this season.
Paradoxically, he is simultaneously Juve’s most important asset and the worst fit for Pirlo’s tactics; a weight around the neck even as he dominates games.
But superstars like Ronaldo are caught in a second, equally uncomfortable, limbo.
The football industry is yet to truly feel the economic impact of the pandemic. Money is scarce around Europe, with even the wealthiest clubs falling into debt as a result of lost income over the previous 12 months: a recent study by the market analyst KPMG suggested more than €1 billion (£855 million/$1.2bn) in revenue has been lost by Europe’s biggest clubs.
It is, therefore, not exactly clear who could afford Ronaldo should he leave Juventus, but nor is it likely the Old Lady can afford to keep him.
There is also considerable doubt over whether any elite club’s tactics would suit his playing style, even if his astonishing numbers would be difficult to resist...
Manchester United
On top of the obvious romance of a return to Old Trafford, Ole Gunnar Solskjer’s side might be the best fit for Ronaldo from a tactical perspective.
In contrast to most super-club managers, the Manchester United coach does not preach high pressing, complex positional interchanges, or the sort of tactical detail that could put suitors off Ronaldo.
Solskjaer lets individualism reign, giving his attackers the freedom to improvise their attacking lines and work out their possession patterns accordingly.
The way Bruno Fernandes has excelled is a perfect example.
The Portugal star, who has worked well with Ronaldo at international level, hit the ground running in England precisely because he was trusted by his manager to develop his own strategy.
What's more, as last weekend's 2-0 win over Manchester City showed, Solskjaer is a strong tactician for games in which United are able to counterattack, but his team can struggle when expected to break down the weaker clubs.
Had United beaten Crystal Palace, Sheffield United, and West Brom this season (just four extra goals would have done that), they would only be four points short of first.
All they need is a bit more firepower – a touch of magic, a goal out of nowhere – for when they’re up against a deep defence.
Edinson Cavani and Anthony Martial have scored 10 league goals between them this season. Imagine how different their season might look if Ronaldo were leading the line...
Real Madrid
Real Madrid have never quite looked coherent under Zinedine Zidane, and while a huge injury crisis has held them back, the Frenchman's team is also suffering from an over-reliance on ageing stars.
Zidane does not use particularly complex tactics and, in that sense, Ronaldo's return to the Bernabeu is plausible.
However, it would be particularly hard for Madrid to justify the colossal expense involved in adding another player in their mid-30s to the team.
Luka Modric, Toni Kroos, and Casemiro continue to hold down midfield, while a misfiring attacking line has been stitched together by Karim Benzema.
It is no surprise, then, that it has become increasingly easy to sit back and frustrate a sluggish, ageing Real Madrid team.
Zidane needs an influx of younger, hungrier players, not the return of one of their greatest ever players.
Ronaldo back at Real would surely be an unwelcome distraction, an albatross further hurting a club that desperately needs to embrace the future.
And the manager is perhaps beginning to do just that.
Throughout Real’s decent run in December and their recent form, Real Madrid have been winning the ball higher up the pitch, attacking more directly, and even trialling more unusual formations with wing-backs turned central midfielders.
It is hard to see how Ronaldo, who very rarely presses, could slot back into his old team.
Paris Saint-Germain
Speaking of pressing, there is surely no way Mauricio Pochettino would sanction a move for Cristiano Ronaldo.
Paris Saint-Germain have a vision for how they want to play football, and while the club are keen on superstars leading the line, they have shown – with the appointment of Thomas Tuchel and now Pochettino – that they wish to embrace verticality and gegenpressing.
As Tottenham fans will know, Pochettino requires young players to enact his Bielsa-inspired vision of breaking the lines with quick, tempo-changing football.
Some already worry that Kylian Mbappe and Neymar may not work well together in a Pochettino team, because while the former is bound to absorb the manager’s methods, there are concerns over the latter.
The financial issues affecting football suggests that no other club in Europe will be in a position to take on either Mbappe or Neymar this summer, and if that’s the case, then there is just no way that even PSG would be able to afford to add Ronaldo's salary to their already sizeable wage bill.
The Juventus forward feels like a PSG signing of a few years ago, not of the side that is now looking to modernise through intelligent tactics rather than glamour signings.
Inter Miami
Inter Miami, though, would obviously jump at the chance to make a splash in MLS by signing a superstar like Ronaldo.
As owner David Beckham said last month, "Without a doubt, [Ronaldo and Messi] are the type of players that we aspire to bring to our club,” he said.
"With Blaise Matuidi and Gonzalo [Higuain], these are players that we feel add to the glitz and the glamour of what the club is.”
Tactically, there isn’t much to talk about. Inter Miami came 10th in the Eastern Conference last year, and new coach Phil Neville is hardly renowned for his tactical acumen.
His England outfit were pretty naive, playing a vague possession game that lacked detail and often made the team worse than the sum of its parts.
Ronaldo may believe he still has a lot to offer at the highest level, but given his talents are no longer a natural fit for modern European tactics, the “glitz” that would come with plying his trade in the US could appeal to him.
The quality is sufficiently low to accommodate Ronaldo playing his own streamlined game and, like Zlatan Ibrahimovic before him, Ronaldo may well revel in the lifestyle of a Miami-based celebrity.