And that’s that! After a summer that has taken Arsenal to the United States, France and now Spain – all eyes turn towards Newcastle.The Gunners completed their pre-season campaign in Barcelona on Sunday night, with a last-minute goal from Luis Suarez condemning them to a 2-1 defeat at Barcelona.Despite the loss, however, it’s been a positive summer on the whole for Arsenal, one that saw a number of youngsters catch the eye. But there have also been some promising signs from the senior players as well. Article continues below Editors’ Picks Emery out of jail – for now – as brilliant Pepe papers over Arsenal’s cracks What is Manchester United’s ownership situation and how would Kevin Glazer’s sale of shares affect the club? Ox-rated! Dream night in Genk for Liverpool ace after injury nightmare Messi a man for all Champions League seasons – but will this really be Barcelona’s? Pierre-Emerick Aubameyang lit up the Camp Nou on Sunday with his goal in the first half, turning well on the edge of the box before thumping a finish into the top right-hand corner to give Arsenal lead.But it was Mesut Ozil’s clever pass that split the Barcelona defence to find Aubameyang, and the German can be very satisfied with the work he has put in this summer.Ozil’s problems last season were well documented. He struggled to adjust to life under Unai Emery and for the first time since moving to Arsenal in 2013 he found himself out of the team at times.And he went into the summer knowing that Emery would ideally like to see him moved on, not least to free up £350,000 a week in wages which could be spent elsewhere.But Ozil had no interest in leaving – something he admitted publicly towards the end of last season – and so he returned earlier in the summer to fight for his place.And that is exactly what he has done since coming off the bench against Colorado Rapids in the opening game of the United States tour.Ozil has looked sharp every time he has taken to the pitch during pre-season. He has demanded the ball, he has run with it with purpose and against Barcelona he showed he still has that quality to unlock a defence.But arguably Ozil’s most impressive work this summer has been when he hasn’t had the ball. He has constantly got forward to support the attack and he has done his fair share of work defensively as well.He looks energised and determined to show he can still be an important member of this Arsenal squad.The arrival of Dani Ceballos this summer on loan from Madrid had many suggesting that Ozil would find himself being pushed further down the pecking order at the Emirates.But with Emery seemingly preparing to go into the new season with a 4-2-3-1 formation, Ozil has the opportunity to flourish in his favoured No.10 role, with Ceballos playing in a deeper role just behind.With the likes of Aubameyang, Alexandre Lacazette and new £72 million signing Nicolas Pepe in front of such creative talents, it’s a mouthwatering proposition going forward for Emery. But the problem for the Spaniard still remains what happens at the back.We saw that again on Sunday in the Camp Nou. Arsenal were comfortable at the break, leading Barcelona 1-0 thanks to Aubameyang’s wonderful goal five minutes before the interval.But things unravelled in the second half, with Arsenal the masters of their own downfall.Defensively they were poor and kept giving the ball away in dangerous areas, inviting pressure on themselves on a regular basis.Eventually they conceded, with Ainsley Maitland-Niles comically rolling the ball past Leno into his own net. And then in the final minute one simple ball over the top saw Luis Suarez run through unmarked to volley home the winner, earning Barcelona the Joan Gamper trophy.It was a game that encapsulated where Arsenal are right now. Impressive going forward, but poor at the back.The transfer window shuts on Thursday, three days before Emery’s side take to the field at Newcastle to get the new Premier League season underway.And you feel if Arsenal are going to take advantage of having such impressive options going forward, then they have to do some more business in the market before Thursday’s 5pm deadline.The clock is ticking.