Edinson Cavani has become such a positive influence on Manchester United's front line it would cost £150 million to replace him.
There are growing whispers that Cavani will return to South America this summer – and that would be a disaster for United.
The Uruguayan forward played with such authority and mastery of his craft against Roma on Thursday night that he was involved in five of United's six goals.
Cavani is not just the best player suited to the No.9 role in the current squad – he is the only player equipped to play with his back to goal.
Marcus Rashford, Mason Greenwood and Anthony Martial are all fine players carrying an attacking threat, but they are best deployed on the shoulder of the last defender and running in behind from wider positions.
Cavani's exhibition against Roma was an experienced, world-class striker at the top of his game.
And it would take a signing of Harry Kane or Erling Haaland's quality to replace him.
Barring a total meltdown in the second leg, United are going to banish their semi-final hoodoo, reach the Europa League final and – in my book – they are favourites to win it.
A first trophy in four seasons, and runners-up in the Premier League, would represent a good season for manager Ole Gunnar Solskjaer.
But it would be a massive setback to lose Cavani – because every time I've seen him play in this United team, he's been the one who made them tick in the final third.
For bringing others into the game, weight of pass, anticipation of mistakes or loose ends in the six-yard box, clinical finishing and running across defenders to attack the near post, he gave a masterclass against Roma.
Just before Cavani made it 2-2, I'm pretty sure I heard Solskjaer telling Mason Greenwood to get ready.
As I said on BT Sport at the time, I thought Greenwood was likely to replace Scott McTominay or Fred, one of the deep-lying midfielders, but you never know how the night might have turned out if United were preparing to bring Cavani off.
What I would say is that United's second-half blitz was relentless – and orchestrated by their oldest player.
Cavani has been the best of the strikers United have signed beyond their prime in recent years.
Zlatan Ibrahimovic, Radamel Falcao and Henrik Larsson, to name three, were all great players, but at 34 Cavani still looks the complete No.9 package.
If he stays – or United replace him with a player of Kane or Haaland's pedigree – I genuinely believe they will be ready to challenge for the title next year if they add a high-class No.6 who can dictate the tempo of games from deep-lying midfield positions.
McTominay has been a real find, but I don't think United will take that final step with both him and Fred holding the fort in midfield.
But for now, Solskjaer can dare to dream of ending four years without a trophy by winning the Europa League – before he confronts the conumdrum of how to keep Cavani... or persuading the board to spend £150m on replacing him.
