Explained: Why new signing Riccardo Calafiori & Jurrien Timber were left out of Arsenal victory over Bayer Leverkusen as Mikel Arteta refuses to take 'risks'

Calafiori was seen in attendance as Arsenal ran out 4-1 winners against the German champions at Emirates Stadium on Wednesday, but neither he nor Netherlands international Timber were named among the substitutes by coach Mikel Arteta.

Calafiori is expected to play a key role for the Gunners this season after joining from Bologna in a £42 million ($53m) move at the end of June, while the north London team hope to see more of Timber after he missed all but two - the first and last - Premier League games last season due to an anterior cruciate ligament (ACL) injury.

Arteta, however, decided against calling on the Italian and Netherlands internationals for the visit of Xabi Alonso's Bundesliga winners, and the manager explained why after the game.

Asked about Calafiori's absence, Arteta explained: "So much has happened to him in one week. He has come in to a new environment, a completely different methodology, different training and we are managing him. We want to do it slowly, to get him in the best possible way."

He was then quizzed on Timber's situation, replying: "He had a little discomfort in his foot the last few days. After the time he has been out, we did not want to take any risks."

Gunners supporters will hope to see the defensive duo in action in the near future, with Arteta's men set to take on Lyon in the Emirates Cup on Sunday. Six days later, they will get their Premier League campaign underway with a match against Wolves.