Arsenal have confirmed that Danny Welbeck will spend a "period of months" on the sidelines due to knee surgery.
The England international had been working throughout the summer to recover from the complaint that he sustained at the end of April.
However, having been unable to step up his rehabilitation work to the required level, it has been decided that the 24-year-old should go under the knife.
The Gunners have refused to put a date on Welbeck's comeback, but they have suggested that he could be out of action for a prolonged stint.
"It had been hoped he would avoid surgery but after increasing his training workload, the injury to his cartilage did not respond as well as hoped and the decision was taken last week for him to undergo surgery by a leading specialist in the field," read a statement on the club's official website.
"Danny is now expected to be out for a period of months and everyone at Arsenal wishes him well."
Welbeck, who joined the North Londoners from Manchester United in 2014, scored eight goals from his 34 appearances last term.