Lionel Messi had a quiet game by his ridiculous standards at Old Trafford the other night - and yet he still was involved in the one decisive moment in the game, where his back post cross to Luis Suarez led to the only goal of the game.
The deflected first-half goal killed this two-legged Champions League quarter-final tie stone dead.
This Barcelona team doesn't compare to the Guardiola era (what team does?) but, in defensive terms, Ernesto Valverde's class of 2019 are a more canny crew.
So it's highly unlikely Manchester United will pull off a 'PSG' at Camp Nou.
The only way to curtail Messi is to administer the kind of crude challenge that Chris Smalling managed to get away with on the night.
It was the kind that had concussive impact.
When you reflect on Smalling's barge that caused the greatest player in the world a virtual whiplash injury, the Barcelona captain did exceptionally well to get to his feet and finish the game.
When Messi has an average game these days it is newsworthy, as opposed to his relentless excellence on a twice-weekly basis.
And while Messi was being examined for a suspected broken nose and possible concussion, Cristiano Ronaldo was scoring his 125th Champions League goal for Juventus against Ajax in their quarter-final first leg.
The Portuguese ace is a freak of nature.
A manufactured footballer – in the most complimentary sense – that has reached his absolute potential. A box-of-tricks-winger who transformed himself into an outstanding goal machine.
At 34, Ronaldo looks undiminished as a footballer and has served the 'Old Lady' well in his first season in Turin as the club tightens its grip on another Scudetto.
Indeed, there is an emerging train of thought that suggests Ronaldo has achieved more than Messi.
Ronaldo, after all, has gone from England to Spain to Italy and proved his league-winning credentials in each posting.
Messi, some argue, has stayed in the relative comfort zone of Barcelona and by doing so hasn't tested himself in different surroundings like Ronaldo.
“Every day Ronaldo makes us a better team,” Juventus boss Max Allegri said.
Respected World Soccer magazine columnist Jim Holden opined there is “something truly precious missing” from Messi's career because he hasn't moved to another league.
“Could he do what Diego Maradona did and inspire a club like Napoli to glory? Many of the other all-time greats have proved themselves at more than one club. Johan Cruyff did so at Ajax and Barca. For Ferenc Puskas it was Honved and Real Madrid. Zinedine Zidane was a superstar at Juventus and Real Madrid…
“Isn't it time,” Holden added, “for Messi to do the same? To take a risk as they all did? To take on the challenge that might actually invigorate his football career and cement a legacy as the greatest of all time? There is nothing left for him to prove at Barcelona...”
There are two questionable underlying assumptions with Holden's analysis. It needs pointing out that, in moving to Juventus, Ronaldo was joining a serial league-winning team.
Juve have won seven Serie A titles in a row. One more win away to SPAL tomorrow afternoon will seal an eighth crown.
It's not like Ronaldo joined mid-table Fiorentina or struggling AC Milan and turned them into league champions.
Juventus currently lead Serie A by a massive 20 points.
With or without Ronaldo, it was preordained Juventus would retain their crown and are equipped to reach a third Champions League final in five years.
Which begs the question: how much value can be added to Ronaldo's achievements by him moving to a club that has a monopoly on the Scudetto?
Throughout his career, successive Barcelona teams have been specifically built around Lionel Messi.
In the early years, the little Argentine was assisted by Ronaldinho and Samuel Eto'o – two outstanding strikers.
When Guardiola took the first team reins, peerless duo Xavi and Andres Iniesta – fresh from their Euro 2008 success – were the men threading balls through to Messi.
It was fantasy football.
But, all the while, observers pointed to Messi's "patchy" form for Argentina as compelling evidence that he would probably not be the same seductive force in another top European league.
Later, Ronaldo would claim a Euro 2016 title with his country.
But what is sometimes missed in the Messi legacy debate, and the fact he hasn't moved to another league, is how highly he has performed for Barcelona since the end of the club's golden era.
Once upon a time Barcelona teams were built around Messi; now, Messi has turned architect.
After Xavi and Iniesta left Camp Nou, Messi's brilliance has made potentially painful transitions much smoother.
A number of radical surgeries have been carried out on the club's midfield.
Some rank average players have come and gone over the last five or six seasons – and yet Messi's performances remain pristine as ever, if not better than ever.
The team hasn't been able to settle on a right back since Dani Alves left the club.
Jordi Alba endured a couple of bleak years at left back.
Gerard Pique has had to compensate – brilliantly, it must be said – for the lack of composure in Samuel Umtiti's game.
And Neymar's high-profile departure didn't have the devastating impact on the Barcelona attack as was initially mooted.
So, rather than wonder what Messi might have achieved in other top European leagues neglects what he's achieved in Barcelona colours in more recent times.
He has won 10 La Liga titles in 15 years, eight of which have come in the last 11 years.
The reason why Barcelona are on the cusp of a Champions League semi-final berth – their first since 2015 – is singularly down to Messi and his incredible evolution as a footballer.
He is chief playmaker and prolific goalscorer rolled into one.
He is the greatest footballer that ever played the game - and no amount of comparative graphs with Ronaldo and goal-scoring stats will change that.