In a cagey performance on Saturday, it took a 94th-minute penalty from Santi Cazorla to finally break down a dogged Southampton defence. By no means a classic, it was nevertheless important to build on the victory at Watford after an indifferent start to the season. The match was notable for a number of reasons, however. We got a first glimpse of new signings Shkodran Mustafi and Lucas Perez, Granit Xhaka was rested as Francis Coquelin played alongside Cazorla, and the performances of Alex Chamberlain and Theo Walcott continued to create debate among Arsenal fans.

I was surprised to see both new faces play. Mustafi came in for Rob Holding, whose performances so far this season have been stellar. It was probably the more expected of the two moves. The club parted with £35 million for Mustafi, making him the fourth most expensive defender of all time. For that price, he is expected to fit right in. The German was shaky to begin with, misplacing a few passes as he took his time to settle into the game’s frenetic pace. He did improve as the game went on, aided by Laurent Koscielny and Hector Bellerin either side of him. At 6ft, he isn’t the tallest of centre halves, and his inability to win headers was worrying. Though Koscielny is only an inch taller, he won almost everything in the air; it took the Frenchman a long time to become the defender he is today. Mustafi seemed very intelligent, and his positioning was good. It wont take him too long to get to grips with the speed of British football.

Lucas Perez started in the number 9 position in an unexpected decision by the manager. With Alexis returning late from South America, his omission was understandable, but I felt that Olivier Giroud should have been given his first start of the season, and he caused the Southampton defence all sorts of problems when he replaced Perez in the second half. The Spaniard struggled, looking isolated at times, shuffling out to either wing and leaving the box empty. He probably isn’t a typical number 9, and will have to improve his movement. He wasn’t helped by the lack of service, and the fact that we couldn’t control the game in the first half. It’ll take time for Perez to adapt.

The decision to start Coquelin over Xhaka or Elneny meant we lacked the quick passing of the Watford game, when Xhaka combined so well with Cazorla, Ozil and Alexis. In the first half we were too slow, Coquelin and Cazorla too deep. In certain games, Coquelin can be redundant, when we need to control the game and retain the ball. He improved in the second half, but I would have liked to have seen Xhaka with Cazorla, though I expect Xhaka will play at PSG.

The game was notable for the choice of wingers, Chamberlain on the left and Walcott on the right. Both players were poor last season, ending the campaign with little confidence. While Chamberlain is still in a rut, Walcott has improved somewhat since last season.

Chamberlain played superbly in pre-season. Of course, players aren’t judged on friendlies, but his quality was plain to see in every match, scoring superb goals and looking confident and direct. Unfortunately, despite scoring in the season opener against Liverpool, his form has not translated into competitive football. Against Southampton, he looked devoid of confidence; when he tried to make things happen, his crosses were invariably overhit. Worryingly, the simple stuff at times eluded him, such as controlling the ball or short passes. He is clearly a supremely talented player, and at 23 still has time on his side. But it needs to click soon.

Walcott received some criticism for his performance on Saturday, but I definitely feel he has grown since last season. He appears more aggressive, helping with defensive duties (he has already attempted more tackles this season than last), and has been slightly more effective going forward, even winning a couple of headers from corners on the weekend. Though subdued against Southampton, there are definitely signs that Walcott is up for the fight to remain in the starting lineup.