Weir suffered the injury during Scotland’s Nations League draw against Belgium on Tuesday and becomes the second Scottish international to rupture their ACL this week, after Manchester United’s Emma Watson.
Weir, who was Real Madrid’s player of the season last year after scoring 28 goals in her debut campaign, is set to undergo surgery in the coming days and is the latest star of the women’s game to rupture their ACL.
The 28-year-old was forced off in the first half of Scotland’s match against Belgium at Hampden, with manager Pedro Martinez Losa criticising the officials after the match for not protecting Weir.
Losa accused Belgium of targeting Weir and said after the match: “I am very angry, we have an injury to our best player, the opponent was looking to deliberately hurt her and it is the duty of the referee to protect the players.”
The confirmation of Weir’s injury comes just a day after Manchester United said Watson had ruptured her ACL during last Friday’s defeat to England.
Watson, 17, had signed from Rangers this summer and had yet to feature for United.