Arsenal's stock of fit left-backs is down to its bare bones with Nacho Monreal's permanent move to Real Sociedad confirmed.
Kieran Tierney is only returning to full training in September and Sead Kolasinac has not been trusted to play in a four-man defence for some time now. Ainsley Maitland-Niles might be yet another option if he were not needed to fill in for Hector Bellerin at right-back.
It may not be the most glamorous position but, as Mohamed Salah's ruthless extrication of Monreal at Anfield last weekend showed, it is one where Arsenal cannot afford to simply make do and mend. In the coming matches the Gunners have games against opponents who could name all manner of dangerous attackers - Heung-min Son, Gerard Deulofeu, Anwar El Ghazi - on their right flank.
Can Kolasinac hold back the tide when he has so often struggled with the defensive requirements of the position? Emery may have no choice but to hope in the short term with Monreal lured back to Spain by a longer-term contract in his native Basque country.
Until such time as Tierney is recovered from what will end up being a lengthy period on the sidelines it will be down to Kolasinac to plug the gap almost entirely on his own, potentially playing all of Arsenal eight games in a 36 day span from early September to the international break. Arsenal would not regret the £3million they got from Brentford for fringe youngster Dominic Thompson but it does mean there is not even a youngster who could step in for Europa League and Carabao Cup fixtures.
Both Emery and Arsene Wenger have found playing Kolasinac in a four-man defence to be a sizeable gamble, one they avoided taking when possible. The Bosnian's greatest contributions by far come when he is on the front foot and, although his crossing is not as accurate as supporters might like, he has shown an impressive ability to get to the byline and create chances for others.
It is at the other end that he has struggled, his relative lack of mobility remorselessly exposed by the Premier League's most fleet-footed wingers. This is not news to Kolasinac or Arsenal, as early as midway through his debut season in English football Wenger was opting to field Maitland-Niles out of position against Salah for the visit of Liverpool rather than allow the Egyptian to attack Kolasinac.
The easy solution would be to simply revert to a back three and restore Kolasinac to his natural position as a wing-back but Emery has made no secret of his desire to use a four-man defence wherever possible. Certainly it would be considered by fans an overly cautious move to pack the defence when Tottenham visit the Emirates on Sunday and one that would only be accepted if Arsenal claimed a convincing victory.
Yet Monreal's departure has not been news to Emery and Arsenal, who have known throughout the summer that the Spaniard was returning home. They have been planning to make sure that they would not be caught unaware if the veteran left-back left.
That much was in evidence throughout pre-season, when Emery made Kolasinac (and Maitland-Niles) play through their difficulties in a four man defence, most notably against Bayern Munich when Serge Gnabry and Kingsley Coman were giving his full backs all sorts of difficulties.
"It’s good to have this problem in the pre-season," he said after the 2-1 win over the German champions.
"Today my objective with Ainsley and Sead [Kolasinac] above all; we were playing lots of matches last year with three centre-backs to allow them to go to the attacking moment. Our target was to work defensively, the first objective is to keep the back four [protected].
"They struggled in one moment because Bayern Munich have very good wingers. But it's good. It's one process for us and them."
That work has continued throughout the early weeks of the season on the training field, where Emery's clear focus has been on improving his defence as a quartet rather than settling for the easier option of bulking up numbers at the back. That work has born dividends with Maitland-Niles, whose improvements have been such that Arsenal did not feel any great need to recruit a right-back to replace the departed Stephan Lichtsteiner and Carl Jenkinson.
Time will tell whether Arsenal have had the same success on the opposite flank.
