By Alex Livie
Last Updated: 01/01/70 1:00am
The former Vitesse Arnhem flyer limped out of the weekend draw with De Graafschap after 72 minutes, and tests have confirmed he has suffered damage to the meniscus in his right knee.
Ajax`s medical team performed stringent examinations and have confirmed that he faces a minimum six weeks on the sidelines.
The news means Sikora will not be ready to return to action until the Eredivisie season resumes in February.
The injury is the latest to rock the plans of coach Ronald Koeman, who also lost star midfielder Rafael van der Vaart in the same game.
Koeman`s options are severely limited ahead of Tuesday`s Champions League clash with Roma and the potentially pivotal Eredivisie match with title rivals PSV Eindhoven next weekend.