Arsene Wenger believes Santi Cazorla's long-standing ankle injury is the worst he has ever seen but refused to rule out a January return for the midfielder.
Cazorla has not played for Arsenal since October 2016 and has undergone eight operations on a troublesome Achilles issue.
The 32-year-old revealed earlier in November that he was told the injury might have left him unable to walk before travelling to his native Spain for further surgery.
Wenger had initially planned to welcome the former Malaga man back into his squad at the turn of the year and remains hopeful that could still be the case.
"It is the worst injury (I have known)," the Gunners boss said.
"It started with a pain in the Achilles and it has gone from worse to worse and I must say I know how much Santi loves to play football and loves to be out there every day and I feel very sorry for what happened to him, because it is unbelievable.
"I saw him one month ago, he was here, and I told him to prepare as well as he can.
"He has competent medical people around him and he tries to practise, but I have not spoken to him recently but I hope he comes back. I left him out of the squad, hoping he would be available in January."
When it was put to Wenger if there were doubts over whether Cazorla would ever play again, the Frenchman replied: "Let's not talk about that, but I hope you are wrong."
Cazorla spoke to Marca in early November and explained the torment the injury, suffered in a Champions League win over Ludogorets, was causing.
He admitted to crying in pain as he tried to battle the issue and revealed that, following initial treatment, he had been told just walking again would be an achievement.
''In the early stages it was feeling a little better, if I got warmed up I could play, but at the break when I cooled down a bit I would cry,'' he told Marca.
''At that time I was still playing and they (doctors) told me it was OK. The problem was that it did not heal and the wounds would reopen and become infected.
''If you're able to walk in the garden with your son again, you should be satisfied, they told me.''
Like his manager, Cazorla was also optimistic he will be back in action in 2018.
''I won't be registered until January, but I will be back by then,'' he added.