Chief executive of Football Federation Australia (FFA) David Gallop has pledged his support to under-fire manager Ange Postecoglou and urged supporters to get behind him. 

Postecoglou has come under increasing pressure after failing to guide Australia to an automatic qualification spot for the 2018 World Cup in Russia, and now faces the challenge of navigating a difficult four-game play-off programme. 

Failure to beat Thailand by three clear goals on Tuesday means the Socceroos must first take on Syria across two legs in October, before facing the fourth-placed CONCACAF nation in early November. 

Despite high-profile names from across Australian football calling for Postecoglou to be relieved of his duties, Gallop is confident that the 52 year-old can guide the nation to its fourth consecutive World Cup.

"We are categorically behind Ange," Gallop said. "We support his desire to see the Socceroos perform well, to win, and to play a style of soccer that is exciting – and we certainly want to see that in these four games.

"Coaches have got the spotlight on them and I don't think the debate hurts as long as people sit back and now realise that it's Ange who's going to take us there and we need to get fully behind him.

"Ange knows what he needs to do to win and we're not there to tell him what sort of tactics to play. They're big games, he's an experienced guy and we're confident that he'll see us through to Russia."