Arsene Wenger has told Mesut Ozil that he has to improve and fill the gap between his own performances and “what he can do”, as wrangling continues over a new contract at Arsenal.

Ozil is expected to return to the Arsenal team today for the away game at Swansea City after missing the last three matches with illness. After a brilliant start to the season, the last few months have been dominated by talk of Ozil’s future and whether his performances warrant the top money that he is demanding from the club.

Wenger has always been Ozil’s biggest fan, after signing him from Real Madrid for £42million in 2013. Ozil was even quoted in Germany last week as saying that he owed his Arsenal career to Wenger, and would only stay at the club if the manager did. Wenger said yesterday those comments had been “misinterpreted”.

But Wenger applied some gentle pressure to his star pupil yesterday, telling the Germany international that now would be the best possible time for him to make himself more useful to the team, starting by scoring more goals. Wenger has been insisting to Ozil for years that he should score, and he has five in the league and another four in Europe so far this season.

“I think what you want of him is to score goals,” Wenger said yesterday. “We all feel certainly that there is still a gap there between what he can do [and his performances]. He is moving in the right way but always, from such a talent, you are maybe a little bit unjust because you always want more.”

Wenger was not critical of Ozil but said a player that talented should always push himself to get to the top. “You feel there is no limitation in his game, so you always say 'come on give us more,'” Wenger explained, “because you always have feeling he can do more. We are all human beings who can improve every day. The problem is that we have to first realise if we want more, how we get more and then after, do it.”

Ozil has been criticised in the past for his body language but Wenger defended him, saying that his own quality is a testament to his hard work. “He has a passion for the game, you do not get the technique he has just by the gift of God,” Wenger said. “You have to focus on every single pass you have made since you were a kid to get that touch, technique and vision. For that you need a passion for the game and he has exceptional passion for the quality of the game.”

There was bad news for Santi Cazorla as Wenger confirmed that the influential Spanish midfielder would not return until March at the earliest. Cazorla had ankle surgery early last month which he hoped would only keep him out for two months, but it is likely to be longer than that.

Ozil is likely to return after his illness (Getty)

“Santi is far from starting to run again,” Wenger said. “He had a little procedure [on 7 December] and we have a meeting with the medical people today to see what it was really. Certainly he will not be available in the next six weeks that is for sure.”