(Reuters) -Tony Popovic was already thinking about the improvements Australia needed to make for next year's World Cup finals soon after they sealed automatic qualification with a gritty 2-1 win in Saudi Arabia on Tuesday.

Popovic took over as coach last September after the Socceroos made a poor start to the third round of Asian qualifying and has overseen five wins and three draws to book a ticket to North America.

"Very, very satisfying right now, I'm sure it'll sink in as the days go by," he said shortly after the final whistle at Jeddah's King Abdullah Sports City.

"It's been a very intense period since I've joined and I've loved it so far. We've done the first part, qualifying automatically, and now the next part is to be bigger and better for the World Cup."

After beating Group C winners Japan 1-0 with a late goal in Perth last week, the Socceroos only needed to avoid a 5-0 loss to the Saudis to take their place in the finals for a sixth straight edition.

They got the job done despite going a goal down in front of a hostile crowd, watching a Saudi player have a red card rescinded by VAR, and conceding a late penalty.

Goalkeeper Mat Ryan, who was winning his 100th cap, saved the penalty to ensure that goals from Connor Metcalfe and Mitch Duke either side of halftime would give Australia all three points.

"To do it here in this atmosphere, you've got to deal with the weather as well, and it's not easy to show that character resilience and then quality, to come back and actually take the lead and win the game," said Popovic.

"For Matty Ryan, his career speaks for itself and there's a lot more for him to achieve ... but it's a day he'll never forget."

Former centre half Popovic was a member of the Australia squad that reached the last 16 of the World Cup for the first time in 2006, a feat matched by Graham Arnold's team in Qatar three years ago.

The 2006 squad had flair as well as the famed Australian resilience, and the task for Popovic over the next year is to build a team that can play a bit as well as fight.

"We've built a good foundation now, and we want to really get better, get better kick on and try and do something special the World Cup," he said.

"We need to play games to keep improving, giving other players that deserve it an opportunity and then we want to be a squad that's much better than what we are now. I think that's the expectation we should have."

(Reporting by Nick Mulvenney, Editing by Peter Rutherford)