Argentine midfielder Flores, 25, scored eight goals and provided eight assists on his way to the A-League top individual award last season.

Flores is now hot property with several clubs overseas linked with his services.

The Reds concede Flores could head overseas on a free transfer if he doesn't agree to a new contract with the club, much like Mathew Leckie did when he signed with German club Borussia Moenchengladbach earlier this year.

"There's a chance (Flores leaves on a free transfer)... that's what we found out with Leckie last year," Coolen told the SA Sunday Mail.

"But that's because we didn't talk to him about a new offer early in the season. I think we've started (the process) with Flores at the right moment. So as a club, you can't do more than that."

Coolen added: “We prefer to have the decision made as soon as possible but, if he needs more time, that's fine with me.”

The 25-year-old only recently returned to Adelaide after holidaying in South America during the off-season.

“He had a very good season," Coolen said. "He showed us that he's not only a key player but also a team player... he does well with the fans and I think he really likes playing for Adelaide United.

"We're trying to do everything we can to keep him here but it's up to him whether that's enough."