The words used to define Diego Simeone’s style all tend to cluster around the same ideas: hard-working, hard-nosed, honest. For the first time in half a decade, however, Simeone’s Atlético Madrid are entering the season with what could be described as a fragile back line.

There was a time two seasons ago when it was almost accepted as fact that Atlético had the best full-back tandem in the world and the best defence overall to boot. Juanfran and Filipe Luis, at once, added velocity to Simeone’s attack and proved impenetrable going backwards, helped out by Diego Godín and whoever he called his partner in the centre of defence. And when all else failed, there was an emerging star goalkeeper in Jan Oblak.

Two seasons on, and Juanfran is losing his grip on the right-back position; in fact, he may lose it entirely due to concerns over consistency and durability. Filipe Luís has limped through preseason with a nagging muscular injury, and seeing as he turns 32 this week, the one area of the field Atlético could always rely on is starting to look suspect.

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On Sunday, Atlético took on Premier League newcomers Brighton & Hove Albion with three of their first-choice back four ruled out. They conceded twice, despite dominating much of possession. Yes, it’s preseason, but the truth is starting to come out: the mainstays in the very foundation Simeone has built his team on are all on the wrong side of 30 with questions marks over their replacements.

Juanfran hadn’t spent more than 17 consecutive days on the treatment table during his entire career before last season and never suffered more than one longer term injury in that time. In 2016/17, the 33-year-old missed over 100 days with two separate hamstring injuries and you have to imagine that those injuries a) are not going to get any better and b) will only continue to slow him down. Never a player who truly relied on explosiveness, Juanfran is now relying solely on guile to get him through 90 minutes, which might not be enough to feature in a system that requires tireless hustle.

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His replacement, Šime Vrsaljko, is still on the mend from a torn ACL he suffered in March and did not train before the trip to Brighton before missing the game completely - a precaution, surely, but he limped out of training earlier in the summer with knee trouble, too. Despite an injury-free 2015/16 at Sassuolo, Vrsaljko suffered five and four injuries in the two respective years prior to that. You would hope that with Oscar “El Profe” Ortega looking over his health now, he is on the other side of these muscular injuries, but the requirements placed on players, and full-backs in particular, in Simeone’s system might be cause for concern with him moving forward.

Real Madrid lured Theo Hernández, Filipe Luis’ heir, ovef to the Santiago Bernabéu and while Atletico have his brother Lucas, he is still not Theo at left-back.

Meanwhile, Filipe did not play against Brighton and did not train in that session either after failing to complete a particularly tasking session in the week leading up to the game in England. The source of the injury is an aggravated soleus muscle, which is one of the most notoriously difficult muscles to repair and get right especially in older athletes.

Real Madrid lured Theo Hernández, Filipe Luis’ heir, ovef to the Santiago Bernabéu and while Atletico have his brother Lucas, he is still not Theo at left-back. Lucas can’t unbalance an entire side with a surging run down the wing like his brother can and will likely be used more as a central defender than on the left.

José Giménez has shown flashes of how good he can be, but just like any centre-half coming into a settled team with a defined set of playing principles, he has been caught off-guard a number of times. Stefan Savić is as prone to an error now as he was during his time at Manchester City, and while Diego Godín is still as dominant as ever, he is entering the winter of his career and will be more concerned with manning his own patch than doing both that and covering for the younger guns in defence this season.

It is what makes the signing of Diego Costa all the more important as Cholo will need to counter the decline of his defensive unit with more goals up the other end of the field. The one upside is that Atlético have improved in that area, with Vitolo arriving in January and, by the looks of things, Chelsea’s outcast too.

Both additions will be good news, because Atlético might be involved in more shoot-outs than ever before in an important year for the club.