Brazil pioneered the back four in the 1950s, withdrawing an extra player to the heart of the defence to give themselves additional cover.
It meant that the full-backs could push out wider, and gave them a corridor in front to push forward. Ever since Nilton Santos charged forward to score a goal in the 1958 World Cup, Brazil have been known for their attacking full-backs.
The evidence of Friday night's game against the U.S., however, is that coach Tite is now looking for something a little different.
It is always difficult to draw too many conclusions from friendly matches, especially those such as the one in New Jersey, when the outcome was never really in doubt. But it can be tentatively argued that Tite has reflected on that World Cup quarterfinal defeat to Belgium and chosen to give his side a little tweak.
An interesting omission from the current squad is Real Madrid left-back Marcelo. He has clearly not been dropped on age grounds. Marcelo is 30; Filipe Luis, who has now become first choice, is three years older. But if he lacks the attacking brilliance of Marcelo, Filipe Luis is steadier in defence.
Just over two months ago in Kazan, Belgium coach Roberto Martinez took full advantage of the defensive deficiencies of Brazil's left flank. Up top on that side was Neymar, whose defensive contribution is limited. Operating from the left in midfield was Philippe Coutinho, more of a support striker than a genuine midfielder. And behind him was Marcelo, whose roving forward runs leave space behind -- and whose defensive game has always been a little loose.
Belgium pushed centre-forward Romelu Lukaku out to the wing on that side, where he found space to pick up possession and give the Brazil defence a very awkward time. It was also from that channel that Kevin De Bruyne fired home what turned out to be the decisive goal.
Tite clearly wishes to retain the Neymar-Coutinho combination. There is obvious logic to this: As seen several times in the World Cup, the fact that Neymar attracts so much marking can often open up space for Coutinho. The pair operating close together can really make the ball fizz.
And so, in the quest for balance, Marcelo is discarded, and Filipe Luis comes in to hold the fort.
The other flank offers further evidence for the shift in emphasis. Until his pre-World Cup injury, Dani Alves played from right wing, rather than at right-back. He would rove and use his constructive talent -- and, like Marcelo, he is happier attacking than defending.
When Alves was injured, Tite explicitly ruled out the possibility of calling up Fabinho, on the logical grounds that the player has since been converted to a central midfielder. But now there has been a change of heart, and perhaps not just because Brazil surprisingly lack strength in depth in the right-back position. It would also seem clear that Tite is looking for different characteristics from the player who fills the role.
True, Fabinho made a forward run that won a (highly dubious) penalty against the U.S. But with Douglas Costa tormenting the left side of the U.S. defence, there was little need for Fabinho to push up the line, as Brazilian full-backs have tended to do in recent decades. Instead, he could stay deep, both to defend and to construct. As Tite said of him after the match, "Fabinho is good in the air, and can help the re-composition of the back four. He is more of a positional player, with good passing skills."
One of the hallmarks of Brazil teams of the past 30 years has been the more defensive balance to their midfield -- necessary to free the full-backs to bomb forward. It would appear that this is being reversed, exemplified by the presence of Coutinho in the midfield trio. And so, to field both wingers and a ball-playing midfield, the full-backs are required to stay deeper -- barring the occasional forward burst as an element of surprise.
Tuesday's game against El Salvador may not provide much further evidence of a switch in priorities. The occasion will probably have much more to do with blooding young players than with the collective balance of the side. But next month's meeting with Argentina already looks interesting. In their 3-0 win over Guatemala on Friday, the young Argentine side featured a pair of wingers and tried to attack quickly down the flanks. They found plenty of space against Guatemala. Maybe Brazil's new breed of more cautious full-backs will be able to slam the door shut.