It was 2006, against Serbia, in a match Argentina dominated and won 6-0. It was his tournament debut and while he wasn't quite the Messi we know now, it is hard to believe that strike, two minutes from time, has been his only goal for his country to date at football's ultimate event.
Since then, he has played seven World Cup games without finding the net. And that is part of the reason why the critics still question his greatness: he hasn't done it on the biggest stage of all. What is interesting, though, is that while this detail seems vitally important to the media, it is less of an issue among supporters. Especially those in Brazil and in particular the 10,000- plus who packed the Argentine training camp on a hilltop over-looking Belo Horizonte last week.
They were almost all locals and they were there to catch a glimpse of Messi. Indeed, apart from Neymar, there aren't many people in Brazil right now who would have generated the hysteria the man from Rosario's presence conjured up.
So much for the idea that rivalry with the Argentines is of paramount importance to all Brazilians. Or that everyone is adopting a "wait-and-see" attitude until Messi does something of note at the World Cup.
Today though brings another test - or, if your glass is half full - another chance to prove himself when Argentina take on Bosnia in Rio de Janeiro. The Bosnians are new to the competition but boast a formidable spine from goalkeeper Asmir Begovic to midfielder Miralem Pjanic to centre-forward Edin Dzeko.
Still, Argentina are overwhelming favourites and the spotlight shines brightest on Messi. The main question for manager Alex Sabella was always going to be to what degree the side is built around the Barcelona man. Do you make him a cog in a machine or do you construct the machine around him?
Sabella has leaned towards the latter, deploying Messi in a front three with Sergio Aguero and Gonzalo Higuain or, alternatively, Ezequiel Lavezzi. Indeed, he has plenty of options up front that he can mix and match based on Messi's form or even mood.
But make no mistake about it; it's still about Messi. He's coming off a disappointing season by his standards: just 28 league goals, his worst tally since 2009 and never mind the fact he still averaged nearly one a game. There is concern about his fitness, worries over wear and tear and, most recently, fears over his tendency to be sick during games. It has happened seven times in the past year and while the medical staff insist there is nothing to worry about, the tendency is to associate it with nerves.
Barring injury, this won't be his last World Cup and he knows it. Yet he may never again have as clear-cut a chance at making history. Which will be guaranteed if he delivers not just on foreign soil, but in - of all places - Brazil.
TALKING of making history, Spain, who achieved that by winning three straight major tournaments, did it again on Friday night, but not in a good way this time, suffering the heaviest defeat of any holders when they fell 5-1 to Holland in a rematch of the 2010 final.
It is hard to tell to what degree the Dutch played well and to what degree Spain self-destructed. There is no question Netherlands manager Louis van Gaal won the tactical battle and that Arjen Robben and Robin van Persie stole the show.
But it is equally true that two goalkeeping blunders from Iker Casillas gifted the Dutch two goals, while the fifth was a classic counter-attacking effort with Spain desperately chasing the game.
The knee-jerk reaction would be to conclude the fire in Spanish bellies has gone out, that complacency has set in, that rather than sticking with the perennial cast of characters (apart from Diego Costa and Cesar Azpilicueta, it was the same crew as 2010) Del Bosque ought to have fully revamped the side.
There is plenty of truth in that, but it's equally true that the Spaniards made some uncharacteristically bad errors and that the tactical misreading on the night probably did the rest. It wasn't just Casillas who struggled. Sergio Busquets, Gerard Pique and Sergio Ramos, the key to their stingy defence, were too easily befuddled by the Dutch forwards. Brazilian-born Costa - mercilessly jeered by the crowd - got the wrong service at the wrong time.
At best, the world champions look headed for second place in Group B, which could well see them take on Brazil in the last 16, throwing up the classic "early final".
When the Fifa rankings deter-mined Switzerland would be seeded at this World Cup, more than a few eyebrows were raised. Also raised were the familiar Fifa conspiracy theories - after all, we all know where president Sepp Blatter is from.
And while it may have been a generous convergence of mathematics - coupled with Italy dropping points at the wrong time - that got them seeded, the Swiss, who take on Ecuador today, could be the "other" surprise package amongst European sides (after Belgium who, really, should not be a surprise at all). It starts with the manager, Ottmar Hitzfeld, who won just about everything there was to win during his time at Bayern Munich. Beyond that, a heavy investment in youth football a decade or so ago is bearing fruit.
Stephan Lichtsteiner and Ricardo Rodriguez may be among the top three or four pairs of full-backs in the tournament. The midfield oozes bite and experience with the likes of Gokhan Inler, Granit Xhaka and Valon Behrami. The main reason Xherdan Shaqiri isn't a household name is that he plays for Bayern and is overshadowed by their front men. And centre-forward Josip Drmic, still just 21, is a dead-eye finisher on the rise.
Many describe the Switzerland-Ecuador game today as a crucial tie-breaker in the hunt for second place in Group E behind highly favoured France.
But, in truth, it might simply be a stepping stone for the Swiss; with uncharacteristic brashness, they are talking about whether they can make the quarter-finals, not whether they can squeeze into the next round as runners-up.