Mikel Arteta could be ready to return to a back three after fielding a three-man defence on Thursday and pointing out the qualities of new Arsenal recruit Takehiro Tomiyasu.The Gunners took on a youthful Brentford side at London Colney in a behind-closed-doors friendly and came out on top.Arteta’s men won 4-0,but it was hardly revenge for their opening Premier League defeat last month. The Bees fielded an inexperienced line-up, while Arteta threw in some of his big guns.Gabriel broke the deadlock early in the second half with a powerful finish from inside the area. Alexandre Lacazette scored the second with a brilliant, curling free-kick before Cedric Soares scored twice late on to give the scoreline a lop-sided look.While Arteta was happy with the work-out, the interesting point to emanate from the training ground was the use of a back three.The Spaniard has not had much joy from his favoured 4-2-3-1/4-3-3 system in the opening three matches. In fact Arsenal’s start has been miserable with defeats to Brentford, Chelsea and Manchester City without scoring a single goal.Arteta did use a three-man defence against City, but that often looked like a back five with Soares and Tierney pushed back. It’s worth noting though that Arteta has had injury problems with Rob Holding and Pablo Mari featuring.Pablo Mari started at Colney with White and Gabriel either side of him in the middle of the defence. Calum Chambers played the full 90 minutes at right wing-back, with Soares on the left.Hungary vs England previewMari and White were replaced, but Arteta gave them the green light afterwards.Yes we had the possibility to play Brentford again. And we had quite a lot of players who needed some minutes. Some of them coming back from injuries, some of them after Covid. So it was a good test and a good work-out, said Arteta.One man who was not used against the Bees was new signing Tomiyasu.The Japan international only arrived from Bologna for £17.2m on deadline day, but Arteta has hinted he could be used in a back three.“Again, we followed him for a while,” said Arteta at London Colney. “We needed a full-back who could be very versatile, can play as a centre back, can play in a back three, Tomi has this capacity.“He is 22 years old but he has some really good experience in Serie A and at international level and with the qualities we are looking for.”It could all point to a more regular switch to a back three. A formation which served Arteta so well in his first season. The stability at the back helped Arsenal to FA Cup glory, whilst also giving his side a platform to attack with freedom. And he could be heading back to that style after a wretched start to the season.READ MORE: Eight wantaway players counting the days until the next transfer window: Mbappe, Lingard, Karius