Adelaide United must negotiate another injury hurdle in their A-League season of promise after senior defender Angelo Costanzo was ruled out for a month due to knee surgery.

Costanzo played through considerable pain in his left knee on Saturday as United claimed their first win in six visits to Sydney with a 1-0 win over Sydney FC.

On further inspection it has been decided that Costanzo will undergo arthroscopic clean-out surgery this week, a procedure likely to keep him out of action until late November.

United coach Aurelio Vidmar said he had squeezed the maximum out of Costanzo's knee for the past three weeks but it was now time to make sure he would be right for the pointy end of the season.

"He's been playing for the last three weeks with a torn meniscus and he's done remarkably well for us to continue in those three weeks with a fair bit of pain," Vidmar said.

"I think we squeezed a good game out of him against Sydney, and if I tried to squeeze another one out of him this week I don't think it would be a smart idea in terms of Angelo's well being and health."

Costanzo adds to an injury list also featuring captain Michael Valkanis and Olyroos striker Bruce Djite, and should require Adelaide to name a short-term defensive signing sooner rather than later.

That player will possibly be tall centre-half Kristian Rees, who was jettisoned by the club in the off-season but has been training with the group for the past few weeks.

In the meantime recent signings Milan Susak and Isyan Erdogan will now be in line to gain more first-team exposure.

"We have been looking through a lot of recommendations and in the next week we should be able to sign someone, even just for the short term and take it from there," Vidmar said.

"We've got Milan who can come in and Isyan who will get an opportunity but we feel we need a backup as well."

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