There was something mystifying about Argentina’s team selection in their victory over Bosnia and Herzegovina on Friday. For the majority of qualifying, they had played a 4-3-3 that seemed ideally balanced and topped Conmebol qualifying.

In the first of their two warm-up games, they played 4-3-3 and impressed in beating Trinidad and Tobago 3-0. And then, unexpectedly, in their final warm-up game against Slovenia, they switched to a back three. The assumption was that the coach, Alejandro Sabella, was simply testing his options, but for their first game at the tournament, Argentina started with a 5-3-2 instead of the 4-3-3.

To the extent that the move had been widely trailed the day before, it was not unexpected, but it was hard to explain. Sabella, who is usually relatively open with the press, was strangely evasive in the pre-match press conference. It wasn’t so much that he wouldn’t say what system he would play—that is only to be expected—but that he said his selection was not to do with how he expected Bosnia to line up but "more with other things, but I can’t say what publicly."

That was enough to set the rumour mill in full swing: Were there cliques within the camp? Had Lionel Messi, whose influence over the squad is a source of great concern to the Argentinian media, demanded to play in a front two with Sergio Aguero?

Even now, a few days on, the selection seems baffling. The most likely explanation is that with Gonzalo Higuain not fully fit and Rodrigo Palacio injured, Sabella didn’t want to risk all three of his fit forwards at once, although given Higuain is close to full fitness and Angel Di Maria could play on the left of the forward line if necessary, it isn’t fully satisfying.

Or perhaps he remembered the friendly last November when his side, playing 5-3-2, defeated Bosnia 2-0 in a friendly. That, though, was at the time when Bosnia played a 4-4-2. Playing a back three against two central strikers makes sense: Two markers with a spare man.

But Bosnia had made fairly clear their intention to switch to a 4-2-3-1 for the Argentina game at least. A back three against a single striker means a marker, a spare man and a redundant player. Sure enough, having fallen behind to that early own goal, Bosnia were able to control possession.

Sabella—correctly—pointed out that his side had held Bosnia at arm’s length relatively successfully, one header from Senad Lulic aside, but that seemed to miss the point: Argentina should, surely, be aiming at rather more than merely holding Bosnia, and if they hadn’t got the break of the early goal there might have been real tension.

As it was, that goal gave them breathing space and, at half-time, Sabella switched to the 4-3-3. Immediately there was more space, for Messi in particular, as Higuain and Aguero pulled defenders wide. That was what created the chasm through which Messi ran to score the second. "

In the first half we gave up possession to Bosnia,” Messi said after the game, “and so I was too deep: I was alone and Kun (Aguero) was alone. It was very difficult. We like [the 4-3-3] better because when you go forward you have more possibilities of passing the ball and scoring. We strikers and forwards are favoured by this formation.”

Sabella, surely, will stick with the 4-3-3 for Saturday’s game against Iran, who showed against Nigeria how well-organised they are. They operate two banks of four very deep, with Ashkan Dejagah dropping back to become a fifth midfielder. Finding space will be difficult for Argentina, which is why they’ll need Messi’s close technical skills in advanced areas, and perhaps the aerial threat of Higuain to prevent Iran dropping too deep.

But that still leaves the mystery of the back five. If it was indicative of discontentment on the Argentinian camp, that could be the snowball that launched the avalanche. If not, it may be the oddest quirk at the start of what could be a very successful campaign. 

All quotations obtained first-hand unless otherwise noted.