Copa America: Lionel Messi and Sergio Aguero dancing in tandem in bid to win elusive title for Argentina

As a welcoming gesture for the Argentine squad when they arrived in Rio de Janeiro ahead of the knockout stage of the Copa America, the host city’s fabled club, Fluminense, had a set of replica shirts made up as gifts.

Each has been printed with the name and number of every one of the 23 Argentine footballers who have been using the Fluminense training ground over the past few days.

The presents were appreciated. Not every Brazilian is so hospitable to these rivals.

Then the jokes began.

Thiago Silva, the Brazil defender and former Fluminense player, asked his old club to "lock up Messi in a cage while he’s there", to keep the Argentina captain from leading his side to a tournament triumph that Argentina’s sluggish form makes unlikely but that an inspired Messi might still conjure.

Meanwhile, weary Argentine cynics muttered about how few players in their patchwork, maddeningly inconsistent squad would actually earn a jersey number at a Fluminense currently hovering just above the relegation zone in Brazil’s Serie A championship. Messi would, naturally, and certainly Sergio ‘Kun’ Aguero. Beyond them … well, it’s debatable, the sceptics reckon.

The most positive aspect of Argentina’s Copa America campaign, which has rattled uncertainly towards Friday night’s quarter-final against Venezuela at Rio’s Maracana, is that results are improving.

After the 2-0 defeat to Colombia came a disjointed draw with Paraguay, then a 2-0 win over guest entries, Qatar, a victory only truly secured, after Qatar had hit the post, by Aguero’s excellent goal eight minutes from full time.

It was the Manchester City striker’s 39th goal at senior level for his country, but his first in a competitive international for almost a year, a puzzling 12 months in which his credentials as the best partner for Messi in Argentina’s attack had been cast into considerable doubt.

Rewind to the World Cup last summer, when Aguero began the tournament in Argentina’s starting XI. Some blessing that turned out to be.

By just over halfway through Argentina’s 3-0 group stage defeat to Croatia, which left them with one point from two matches, he had been bumped down the hierarchy, behind Gonzalo Higuain. He reappeared only as a substitute after that, his final act the injury-time goal that pulled a ragged Argentina back to 4-3 down against France in the wild, frenetic last-16 defeat.

After that, he was cast out into the cold.

But Aguero, unlike Higuain, did not retire from international football, despairing though he might have been about more than a decade of service without any reward in terms of gold medals. Higuain vented his frustration at perceived wrongs. “My time is up,” Higuain announced in March, adding waspishly, “to the relief of many people, no doubt, who remember the goals I missed and never the ones I scored”.

But Aguero merely kept his counsel when, month after month, he was excluded from new manager Lionel Scaloni’s squads, even as he was propelling Manchester City towards his fourth Premier League title with a fifth successive 20-plus league-goals season.

“It’s not my turn right now but I am always available,” Aguero said when Scaloni opted for yet another ‘Kun’-free squad for the spring friendlies that seemed to finalise the candidates for the Copa campaign. But when, in Madrid that month, Argentina were beaten 3-1 by Venezuela, Messi is understood to have quietly mentioned 31-year-old Aguero’s name to the manager, with a gently questioning tone.

Messi-Aguero; Leo and Kun: The pair, a year apart in age, go back a long way, to when they were teammates in Argentina’s age-group teams and success seemed almost routine, rather than the tantalisingly remote dream it has become as grown-up internationals.

Messi, who turned 32 earlier this week, and Aguero won the World Under 20 Cup as teammates in 2005. They were Olympic champions together in 2008. In the 10 years since, the best they have done is a lost World Cup final, in 2014, and two losing Copa America finals.

There have been too many dysfunctional evenings in the stripes of Argentina that the failure to click consistently, and brilliantly, is not bewildering.

But is also plausible that, had the relationship been cultivated more regularly at senior level, and Aguero been established as Messi’s best possible partner ahead of a range of alternatives - from Carlos Tevez to Higuain to Mauro Icardi over the years - these strikers, men who have dominated the two strongest leagues of Europe - Spain’s and England’s - for so long might have operated better together.

After all, they have both advanced as footballers under the same guide, Pep Guardiola, who worked with Messi as he emerged as a peerless No 10 at Barcelona, and who has drawn from Aguero a more rounded game in the last two years at City.

Now, perhaps, is the moment, the time to dance, in happy tandem, to Argentina’s rescue.