The Matildas star played in pain throughout much of her team's courageous 2-1 win over Melbourne last weekend but will now be forced out in order to protect her future.

Sydney FC play Adelaide today at Hindmarsh Stadium. Garriock will be missing and could spend considerable time on the sidelines, depending on how she responds to treatment.

"I'm a bit upset," she said just after seeing her physiotherapist on Friday.

"It's a fairly bad injury and if I want to nurse it through the season I could, but that means there could be repercussions for next year when I go the United States [to play in the new professional league]. I'm definitely out this weekend and probably for the next month or so. After that I'll have to make a professional decision and work it out with my doctor."

It's a big blow for the team which has battled through losing five players and coach Alen Stajcic, who were representing the Young Matildas last week.

They beat Melbourne with a late winner last round to maintain their perfect record after two rounds.

"The team's gelling really well even though we struggled a bit last week," Garriock said. "Everyone's back this week though. We haven't done any real shape work yet, which has made it tough, but we've done OK anyway, with two out of two. It has helped to have experienced players."

Garriock said one of the most impressive players had been striker Leena Khamis, who has scored three goals in two games.

"She scored a really important winner for us last week and twice in the first game," Garriock said. "She's finishing off her chances and probably being noticed by [Matildas coach] Tom [Sermanni]. She's been plodding away but now the W-League has given her a chance to shine and she's taking her chances."