The Socceroos marked their debut in the tournament on Sunday with a disappointing 1-1 draw with Oman, only avoiding defeat thanks to Cahill's 90th-minute strike.

It was the Everton star's first competitive action in three months after breaking his fifth metatarsal while playing for his club in March.

Kewell, meanwhile, made his return to the starting XI after recovering from septic arthritis in his left foot, an injury that kept him sidelined for much of last season with Liverpool.

And Emerton believes the duo will only get better as Australia look to secure a much-needed three points ahead of their crucial Group A clash with Iraq on Friday.

"They (Kewell and Cahill) are two world class players and having them in the squad is a major bonus for us," said the Blackburn player.

"Harry got through his first 90 minutes unscathed and he has been looking good in training since then and so has Tim.

"Like each and every player in this team, as the tournament progresses they will get fitter and stronger and it's great to see them back playing for the national team.

"They can turn games on their head and if we want to do well at this tournament, they are the types of players we need in this team."

Though disappointing, Emerton believes their draw with Oman could provide the springboard to propel Australia through the group stages and into the next round.

Iraq are likely to provide an even bigger test as Jorvan Vieira's side look to take a big step towards the quarter-finals for the fourth consecutive time.

And Emerton insisted Australia need to defend better as a team if they are to secure the victory they need.

He added: "Defence starts from the front line, it's not only the back four's job to defend. It starts from the front and midfield.

"It's a team job so I think everybody can improve defensively. It's something we have been working on and slowly but surely we should get better.

"We are not taking them (Iraq) lightly. The first game against Oman proved that each game in this competition is going to be very difficult for us.

"Maybe the first game was a major wake up call for us and it came at the right time.