Coolen was stripped of the manager's position with the Reds and made Head of Youth Development last season having led Adelaide to five defeats in the opening 11 rounds, while John Kosmina took over the head coaching role.

But Coolen quit within days and almost immediately began his quest for reimbursement, which has culminated in the first day of his civil trial against the club today.

In November 2010, having led Adelaide United to the A-League finals in the 2010/11 season, Coolen signed a new contract with the club until 2015.

But just 13 months later, Coolen claims the club asked him to resign to avoid a costly payout, only for the manager to refuse.

Having been replaced by Kosmina and given the youth development job, in what Coolen's legal representatives described as 'the first of many episodes of backpedalling by the club in trying to make lawful its unlawful objective', the former FC Twente manager quit.

Coolen claims he has been denied almost $1.3 million in salary plus benefits and bonuses, including payment of his children's school fees, which add up to $2.2 million.

Adelaide United have counter-sued based on accusations Coolen lied during contract negotiations, citing the offer of a job in Japan.

Coolen's Australian visa is set to expire this week.