The forward was forced off after 27 minutes of his side's 2-2 draw with Barcelona in the Champions League quarter-final on Wednesday night after suffering a calf injury.
The Gunners are yet to reveal the results of a scan, but Arshavin admits he fears a tear will rule him out till the start of the next campaign.
Blow: Arshavin is replaced by Emmanuel Eboue against Barcelona
The Russia captain said after the game that he could be back in a fortnight, but now he expects a longer lay-off.
'I pulled my calf muscle and, it seems, tore it,' he told Russian newspaper Sport Express. 'If the scan confirms the initial diagnosis, as seems most likely, I'll be out for a long time.
'At best I'll be back in three weeks, at worst I won't play again this season at all.
'(William) Gallas suffered a similar injury. He was treated for three weeks in England and then three more in France. He only just recovered, played against Barcelona, and is now out of action again.
'We didn't play the way we wanted and now I've got myself into this mess.
'I could have easily missed the game because of pain in my groin, but I had a jab and was able to play. But fate, it seems, was against me playing Barcelona.'
Gunners skipper Cesc Fabregas is definitely out for the season after breaking his leg against Barca while Wenger is already without Robin van Perise and Aaron Ramsey.
Despite the crowded treatment room, Arshavin remains upbeat about his side's title chances.
Huge loss: Arshavin was in determined mood before picking up his knock
He added: 'Our rivals also have absentees - for example, Wayne Rooney is out. A lot will depend on what happens when Manchester United and Chelsea play each other on Saturday.
'I hope for a draw. Then we would be trailing by two points and one point respectively. If Chelsea win it will be one and three. If Manchester United win, making up four points on (Sir Alex) Ferguson's team would be extremely difficult. And in the long run there is no difference between second place and third.'
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