Alex Oxlade-Chamberlain has rejected Roy Keane’s claim that Arsenal cannot win the Premier League because too many of their players are “interested in selfies” and care more about how they look than securing victories.

Oxlade-Chamberlain said Arsenal’s Community Shield win over Chelsea had put down a marker for the season, as his side aim to improve on third place in the Premier League behind José Mourinho’s side and Manchester City. He struck the only goal of the game at Wembley and said the squad are the most confident he had been involved with at the club.

Asked about Keane’s weekend remarks regarding selfies, Oxlade-Chamberlain, 21, said: “It’s a new era, isn’t it? Some people do it, some don’t. We’re serious about winning trophies. Personally, and I can speak for the rest of the squad, we’ve been serious every single year I’ve been at the club about winning trophies.

“You can see that on the pitch. A lot of people don’t see when we lose and go through tough times how upset and disappointed we are. We’ve always wanted to win trophies and in the last years we’ve won a few. This season we want to go that one better.”

The England international described the belief in Arsenal’s squad as being the strongest since he joined in 2011. “We’ve all been together a good number of years, we’ve shared two consecutive successes in the FA Cup and we’ve had the highs and the nice feeling from that. That always helps. As a team we’ve suffered some upsets as well and I think we’ve grown from that and learned.

“It was what we needed against a good Chelsea outfit after the season they had last year. It’s important for us to come into these fixtures and lay down good foundations and good markers. I’m glad we did that at Wembley.

“It does help the confidence and that belief and faith going into that next fixture against them. Against any of the teams at the top of the table, that helps but it is a long season and it is very early doors. We can’t get too carried away with that but it is a good end to our pre-season which has gone really well.”

After Arsenal’s victory – their fifth out of five pre-season matches and one which ended a run of 13 matches without a win for Arsène Wenger against Mourinho – Oxlade-Chamberlain emphasised the need for results against the top sides: “José is a fantastic manager. He’s shown that over a number of years and he puts out great sides – he’s got great tactics.

“It’s important we can compete with those teams and we’ve always got to try to go one better and win. We managed to do that this time and that’s good but we can’t get carried away. I’m sure we’re going to have a few more fierce competitions and fierce games against them this season.”

In a quiet summer for incoming transfers at the Emirates, Arsène Wenger recruited Petr Cech from the champions and the goalkeeper put in an impressive performance against his former club. Yet Oxlade-Chamberlain said Cech offers more than just stability between the sticks. “The addition of Petr Cech will certainly help us, he’s a quality player. He is an individual and a character who has won things – that’s another one with the winning mentality getting in our squad and it can only help us.”

The forward hopes a mixture of luck and hard work can bring a more consistent season, after a combination of hamstring and groin injuries restricted him to 17 league appearances in 2014-15.

He said: “I feel good. You know what football is like – you can never speak too soon, so I take each game as it comes. I’m putting in the work off the pitch and fitness gives you the platform and allows you to do the things you want to do. So, fingers crossed I have better luck this season.

“The medical and fitness teams have been really good, not just for me but all the boys through pre-season. I believe we’re all at a good level physically. We’re not 100% there yet – that comes a few weeks into the season but they’ve done a really good job on us and I feel good. Fingers crossed we stay in good nick and it gives us a good chance for the season.”