Tata Martino is well aware that he's in a peculiar position.
"I know where I was born," the Mexico coach told reporters on the eve of Saturday's monumental showdown with his native Argentina.
"I'll tell you the year, the name of the hospital, the city's area code. But I have to do everything possible for Mexico to win."
And to do that, he needs to stop Lionel Messi, a man he previously coached at Barcelona.
"The best footballer of the last 15 years, at least," Martino declared. "When it comes to stopping him, it's more often because he's having a bad afternoon than what the opposition does."
Messi can ill-afford a bad afternoon at the Lusail Stadium. His World Cup legacy is on the line.
There can be no excuses. This is arguably the best – or at least the most united – Argentina side he's ever played.
They had arrived in Qatar on a 36-game unbeaten run. The all-time international record was within their grasp.
And yet they opened their campaign with a 2-1 loss to Saudi Arabia – a team 48th places below them in the world rankings.
As shocks go, it was right up there with the biggest in World Cup history.
Lionel Scaloni admitted his players were "all in pain" as they sat in stunned silence in the dressing room.
They weren't the only ones struggling to process the defeat. One Argentine journalist could be found in tears in the mixed zone after the game.
"A sad day," as Scaloni conceded.
It had started so well, though, with Messi coolly making amends for his penalty miss in Argentina's opener against Iceland four years ago by rolling home a soft spot-kick.
However, they subsequently failed to get the measure of Saudi Arabia's high line, seeing three first-half 'goals' ruled out for offside, and paid a heavy price, with Saudi Arabia pulling off a seismic upset thanks to Saleh Al-Shehri and Salem Al-Dawsari.
"It is difficult to understand because in four-to-five minutes, they scored twice," a clearly shell-shocked Scaloni lamented. "I think they were the only shots on goal."
If the Saudis had rode their luck, though, there was no denying that the Argentines had failed dismally to respond to adversity.
So many players underperformed. On ITV, former Manchester United captain Roy Keane was left astounded by Angel Di Maria's abject display, while Cristiano Romero was so bad that he was replaced early in the second half.
The midfield was a horror show, though, with Leandro Paredes and Rodrigo De Paul looking exactly like what they are: two men who haven't played regular football this season.
It was Messi, though, who unsurprisingly bore the brunt of the online criticism.
His GOAT status was mocked and there were the usual unflattering comparisons to Diego Maradona, even from the great man's son.
"The comparison between Messi and my dad is made by those who don't see and don't understand football," Diego Junior argued on Radio Marte. "We are talking about two different planets."
He's obviously a little biased and Messi's greatness shouldn't be defined by one tournament – but there's no denying that his World Cup legacy would be tarnished by an embarrassingly early exit from his final tournament.
Nobody is writing Messi off yet, though. Not even Diego Junior.
"I don't rule out Messi making his mark," he added. "Sometimes in football it happens that you lose even against much weaker opponents.
"If you don't close the games, even the poorest teams will come at you."
Argentina certainly paid a heavy price for being repeatedly caught offside against Saudi Arabia, and they will need to be far more precise against Mexico, and not just in terms of the timing of their runs, but also their shooting.
They are, after all, going up against a goalkeeper that always seems to turn into a mix of Lev Yashin and Dino Zoff every time a World Cup rolls around – Guillermo Ochoa.
And the bad news for Argentina is that after earning his country a precious point against Poland by saving a Robert Lewandowski penalty, Ochoa is now actually looking forward to facing Messi.
"Leo has that magic, he can do nothing and from one minute to the next he can solve things and score a goal," he explained. "But it's going to be a nice challenge.
"It's going to be very difficult but what better stage than a World Cup against one of the best players in history, if not the best."
For some, though, Messi is missing one of those truly magical World Cup moments that all of the game's greats have on their CV.
Remember, the seven-time Ballon d'Or winner has yet to even score a goal in the knockout stage, and Argentina are now at risk of failing to even make the last 16 at Qatar 2022.
It shouldn't all come down to one man, of course. Both Scaloni and Messi himself say Argentina need to remain united, now more so than ever before during their record run.
They need to take collective responsibility for the surprising situation that they found themselves, and work together to get themselves out of it.
But the captain clearly has to lead by example against Mexico. There have been whispers that Messi's not fully fit, that he's been hampered in training by a minor niggle.
But Scaloni says his skipper is fine, physically and mentally.
Nothing less than a decisive display will be tolerated; such is the fickle and unforgiving nature of football today. GOATs don't go out in the first round, after all.
Rightly or wrongly, then, this one's on Messi. He has to save Argentina – and his World Cup legacy.
Over to you, Leo...