Arsenal in trouble: absence of 'the rock' exposes Arteta's most serious weak point

Arsenal have conceded 2.3 goals per game across the three friendlies they have played since the start of August, their net breached six times in the last two matches alone.

Set that against last season's Premier League record of 1.4 goals conceded per game and the figure looks even more alarming.

For more than three years, Arsenal had not conceded three goals or more in two consecutive matches, whatever the competition. That makes this pre-season an unusual one for the London club.

Arteta can, of course, point to the nature of friendlies. They are a chance to try out ideas and formations, and to make mistakes before reaching full readiness. As the weeks pass, players regain their fitness, the intensity rises, and the understanding between new and old faces improves.

The Spanish coach also has a clutch of key players filtering back into the squad. He must bed in his latest signing too. Bruno Guimaraes is expected to play an important role alongside Declan Rice, shoring up midfield and easing the pressure on the back line.

Still, Arteta can't ignore the defensive gaps that opened up during Sunday's defeat to Borussia Dortmund, even though his back four represented the strongest option from the players available to him.

Gabriel returned to action for the first time, slotting in for Piero Hincapie at the heart of the defence. The Brazilian's presence still wasn't enough to plug the problems.

If anything, fresh positional errors crept in. Gabriel and Cristhian Mosquera both made glaring mistakes, exposing a flaw in the defensive organisation rather than a simple lack of individual quality.

Saliba's absence, it seems, cut deeper than anyone expected.

Expect Arteta to stick with the same back four against Manchester City, having played a final friendly against Como on Wednesday. That gives him one more chance to iron out the weaknesses before the anticipated clash at Wembley.

The Spaniard knows his side must hit peak readiness. The meeting with Manchester City hands him a chance to land an early blow over one of his most prominent direct rivals.

The Charity Shield may hand out only a symbolic title, but a contest of this kind matters for a side looking to stamp its authority on the season from day one.

Arteta, the longest-serving manager currently in the Premier League, won't get the patience and leniency afforded to someone in his first season, like Enzo Maresca.

The Manchester City fixture marks the 353rd match of Arteta's managerial career. That figure lays bare the scale of the experience and the expectations resting on him.

Defeat to Dortmund clearly stung, and Arteta made no attempt to hide it despite the friendly nature of the game. He called the loss "painful".

"We conceded poor goals in the last match, and more poor ones today, particularly in relation to the way we competed and performed," said the Spanish coach.

Those remarks betray a clear awareness that Arsenal remain a long way short of the sharpness and ferocity Arteta demands from his players.

The problem may be simpler than it looks. Arsenal shipped six goals across the games against Real Betis and Borussia Dortmund. Three came from shots outside the box, two from corners.

Those numbers expose an unusual breakdown in positioning and organisation the moment Arsenal lose the ball, and they underline how much work the set-piece defending still needs.

Midfield tells the same story. Declan Rice's return should sharpen the defensive roles and responsibilities there, with Bruno Guimaraes and Martin Odegaard alongside him.

That trio hands Arteta more ways to control the middle of the park and rebuild the balance between attacking build-up and defensive security, something his side lacked at times during pre-season.

Arteta has spent recent weeks sharpening the creative side of his midfielders and playmakers. At certain moments, though, that focus has cost the team its defensive solidity.

Arsenal drew heavy criticism last season for leaning too much on set pieces to settle tight matches, with their attacking threat in open play drying up at times.

Recalibrating that equation was essential, particularly with the team going into the new campaign as reigning Premier League champions and everything that demands in terms of a more varied brand of football.

Arteta also has far greater scope now to rotate his line-up without diluting the team's quality to the same degree. That flexibility could help him develop his style gradually.

Any expected progress under Arteta hinges on his ability to deliver a more effective and exciting possession game. Chance-creation rates across the recent friendlies suggest the team is already heading that way.

Sharpening the attack cannot come at the cost of defensive solidity, though, especially now that the side has lost one of the key cogs in its defensive system with Saliba out.

This week hands Arteta his first chance to work with a squad closer to full strength, as the World Cup contingent and the England internationals return to training.

The biggest challenge facing the Spanish coach is plugging the defensive gap that showed up so clearly during pre-season, and finding a stopgap for Saliba's absence before it turns from a temporary problem into a genuine weakness that threatens Arsenal's start to the new season.