The defender told the Adelaide Advertiser his career at the Reds was at the crossroads after he was ‘rested' from the senior side during the game against Perth Glory last weekend.

Coach Aurelio Vidmar had a chance to clear the air in a midweek media conference but instead was non-committal about the 32-year-old.

He would not say whether the veteran would regain a spot in the senior side to play Sydney FC at Adelaide Oval on Saturday or whether he'd be chosen for the club's National Youth League team which plays earlier that day at Hindmarsh Stadium.

"Don't know, you'll have to wait until the end of the week," Vidmar said on upcoming selections.

Vidmar also said the team wouldn't be making official its planned changes to the squad until later in the season.

"We'll be making decisions in the next month or two and that still gives me a number of weeks," he said.

"At this point of time no information will be coming out from us."

Costanzo joins a list of Reds players that have either decided to, or are considering, leaving South Australia.

Jason Spagnuolo will play for North Queensland Fury next season while Brazilian Diego told Sportal last month he was disappointed the club hadn't offered him a new contract.

The impending retirements of Michael Valkanis and Paul Agostino also ensure the Asian Champions League finalists will take on a new look next season.

Changes aside, Adelaide have proven to be strong performers this year regardless of their off-field demands or distractions.

Last week they managed to beat Perth Glory 1-0 in their comeback game after the Club World Cup and this Saturday they want to secure another three points against a misfiring Sydney FC.

"Sydney are in pretty good form regarding their playing time on the park ...except the results," Vidmar said.

"And I know certainly one day it will change because they can't go on for that long without the right result. We hope it's not this week.

"By getting a result on Saturday we certainly send out a statement."

Vidmar was also expecting an out-of-sorts John Aloisi to have an impact.

"The more he goes without scoring, the more dangerous he gets and he'll be fired up certainly if he gets the opportunity," he said.

"That'll be eating at him he'll certainly want to make amends very quickly."