Wenger left to sweat on Arsenal’s defensive weakness

Arsenal have been here before. Twice in the previous three seasons they have made the trip to this blue-collar German city to take on Borussia Dortmund in the Champions League group phase. The memories are fond.

In 2011 there was the creditable 1-1 draw at the steepling Westfalenstadion – Arsene Wenger’s team were denied by the substitute Ivan Perisic’s stunning 88th-minute equaliser – and last season there was the 1-0 smash-and-grab victory which represented Dortmund’s only ever home loss to English opposition in Europe.

Both Arsenal performances were underpinned by defensive steel, particularly the one last November, when Per Mertesacker and Laurent Koscielny put their bodies on the line time and again. They provided the defining images of the occasion as much as Aaron Ramsey, who headed the decisive goal.

Wenger used the same goalkeeper and back four in both ties – Wojciech Szczesny behind Mertesacker and Koscielny, with Bacary Sagna and Kieran Gibbs as the full backs – and it stands to be broadly similar this time out, as Arsenal kick off their 17th consecutive group stage campaign in Europe’s elite tournament.

Sagna is gone, having taken the well-trodden path to Manchester City over the summer, but the other stalwarts remain, with Gibbs having regained fitness after his latest pulled muscle. He stands to return to the team in place of Nacho Monreal, who has a minor back strain.

Defenders like to play regularly together

and it is fair to say that Wenger’s chosen unit will have ample opportunity to do so. This, at least, is the positive reading. The negative one highlights the absence of many real alternatives and paints a worrying picture of how Wenger’s defensive resources stand to be stretched over the coming weeks.

When Mathieu Debuchy, the right back signed from Newcastle United to replace Sagna, got his studs caught on the turf towards the end of Saturday's Manchester City match, twisted and fell awkwardly, it was immediately clear that he was in big trouble.

Wenger spoke about a "bad ankle sprain" after the game and here he confirmed that Debuchy would be out "for a longer period". He said that he did not know precisely how long and he continues to hope for a favourable scan result, but the indications have been that it will be months rather than weeks. "I'm just very sad for Mathieu," said the midfielder Mathieu Flamini.

Debuchy had started in four of France’s five matches at the World Cup in Brazil, culminating in the quarter-final defeat by Germany on July 4th, and since the beginning of the new season he has started in all of Arsenal’s seven matches (including the Community Shield against City on August 10th) and played in one more match for France. Did tiredness blur his focus when he got himself into the tangle on Saturday?

Debuchy would not have played in Dortmund after his sending off in the play-off second leg against Besiktas, but Wenger’s defensive headache has been deepened by the bout of tonsillitis that has afflicted Calum Chambers.

With no Debuchy, no Monreal and possibly no Chambers, Wenger is short of options at the back and he was hardly in the position to lose any in the first place. It was his decision to leave the summer transfer window with five senior defenders in his squad – plus Chambers, who is on the Under-21 list. Now there are only three, plus Chambers, and it is no exaggeration to say Wenger is struggling to name a back line. He has included the 19-year-old academy right-back Hector Bellerin in his travelling party but given that the Spaniard has played only 26 minutes for the club in the Capital One Cup, it would be a huge gamble to use him. Bellerin is extremely quick but equally raw.

If Chambers does not make it, Wenger may play Flamini as an emergency right

back, but it begs the questions as to how the manager could have allowed such a situation to develop so early in the season.

Wenger decided not to pursue another central defender after Chambers – who played only at right back at his previous club, Southampton – started the season so promisingly in central defence and he believes that Monreal can also cover as a left-sided centre half. The decision seemed risky, even at the time.

Arsenal’s fans have started to wonder whether the midfielder Francis Coquelin can provide an option at right back and if the academy prospect Isaac Hayden can do likewise in central defence.

They are praying for another resilient showing against Dortmund from what continues to bear the imprint of their established defence. It is what lies beneath, or otherwise, that is of mounting concern. Guardian Service