Sead Kolasinac has the steel Arsenal need to end their run of five defeats at Stamford Bridge but Arsène Wenger must play him on the left and stick to three at the back

Arsenal fans will travel to Stamford Bridge on Sunday with a dram of hope, even though they know that by most measures their spirits should be low. Recent visits to Chelsea have been harrowing for the north London club, with Arsenal losing their last five matches there by a combined score of 15-2. Both their away games in the Premier League this season have brought similar ordeals, with Liverpool thrashing them 4-0 and Stoke City punishing errant finishing and flaky defending to inflict a 1-0 defeat. A strong case can be made for dismissing Arsène Wenger’s timid travellers right now as “same old Arsenal” and not even bothering to watch their inevitable defeat against Antonio Conte’s side on Sunday. But where is the joy in that?

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It is more entertaining to give Arsenal the benefit of the hefty doubt and instead look to the reason why they might make a contest of their trip to the champions. Those reasons are not so hard to find. For a start Arsenal have beaten Chelsea in their two most recent meetings, both at Wembley. And both wins were deserved, too, as Arsenal were the better side in May’s FA Cup final and again in last month’s Community Shield, even if the second victory was by dint of a penalty shootout.

The other reason is that Arsenal have become less predictable – in terms of their formation at least. It used to be fair to criticise Wenger for playing exactly the same way against every opponent no matter what but the Frenchman has developed flexibility to the extent that Conte cannot be quite sure how Arsenal will line up.

They finished last season at an encouraging clip after Wenger took inspiration from Conte’s preferred formation and switched to a three-man defence, an uncharacteristically radical shift that yielded 10 wins from their last 11 matches, including the FA Cup final. Wenger has used that pattern again this season, including in the Community Shield, but he has also reverted to a back four at times, notably in Thursday’s Europa League comeback victory against Cologne, when Arsenal, losing at the break, were transformed by the change of tactics at half-time.

Wenger explained after the 3-1 win over the German team that flipping to a back four enabled Sead Kolasinac, whom the manager introduced at left‑back, to collude with Alexis Sánchez down the left wing. Both players scored as Arsenal overwhelmed the visitors.

That second-half performance – and the suspicion that Wenger remains a back-four man at heart – has heightened expectations that he will start with that scheme at Stamford Bridge in the hope of forcing Chelsea’s wing-backs, Marcos Alonso and Victor Moses, to spend most of their time defending. That would be a daring ploy, banking on Arsenal to attack with enough regularity and sharpness to prevent Chelsea from establishing central dominance before pulling the visitors’ exposed back four apart. For “daring”, one could read reckless. It would be shrewder to stick with three central defenders for this match. That is the formation Arsenal used when beating Chelsea in their two most recent matches.

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Either way it is essential that Kolasinac starts. Personnel and attitude are more important than formation, and the free signing from Schalke has shown he has the skills and precious steel that Arsenal sorely need.

The problem with Wenger’s new‑found flexibility is that it does not always seem well-founded; it can seem a touch random when it leads to players playing in positions to which others would be better suited. For instance, one of the reasons why the switch to a back four in the second half at Stoke did not work as well as it did against Cologne was that, when implementing it, the manager removed Kolasinac (who had been at centre-back) and asked Héctor Bellerín to operate as a left-back while Alex Oxlade-Chamberlain improvised on the right.

Kolasinac, bizarrely omitted entirely at Anfield, must start at Chelsea either at left wing-back or left-back. Those are the roles in which he can do most damage to the opposition and provide the most security to Arsenal. Victor Moses and Eden Hazard or Pedro Rodríguez would certainly prefer to face someone less fearsome and relentless, someone more likely to crumble in the manner of same old Arsenal.

• This article has been corrected. The original standfirst said Sead Kolasinac is Serbian – he is from Bosnia.