In Australian football's worst-kept secret, Arnold will take over from Dutchman Bert van Marwijk after the World Cup in Russia and is expected to see Australia through until the 2022 World Cup.

That will include the Socceroos' Asian Cup defence in the United Arab Emirates next January.

Arnold has long been a favourite for the role on the back of his record-breaking success with the title-winning Sky Blues.

The 54-year-old will leave the A-League club at the end of the season to return to the national team set-up for the first time since coaching the Socceroos for 12 months following the 2006 World Cup.

The announcement is expected to come hours after Sydney were dealt a near-fatal Asian Champions League blow, losing to group opponents Kashima Antlers 2-0 at Allianz Stadium.