Former Australia national team goalkeeper Zeljko Kalac has joined the chorus of people who have recently sang the praises of current shot-stopper Mark Schwarzer.

Kalac, who enjoyed a successful career with clubs like AC Milan and Roda JC in Europe, believes Schwarzer is in career-best form and has backed to continue playing at highest level for some time to come.

"Why would Mark want to quit the national team or football in general?" Kalac asked.

"He's just come off a great season with Fulham where he played in the Europa League final, and he is playing as effectively as ever.

"His career pretty much started in earnest 12 years ago when he moved from Bradford to Middlesbrough (after beginning his overseas odyssey with German clubs Dynamo Dresden and then Kaiserslautern).

"He really didn't do much before that, but he's made up for lost time, that's for sure.

"In that sense he is still quite fresh. The really scary thing for Australian football is that there is nobody in the national set-up really challenging him."

And Kalac added that he believes the 37-year old has a monopoly on the number one position for the Socceroos.

"He looks like he can have the job as long as he wants.

"Maybe I will have to come out of retirement and give him some competition again because he's not getting it from anywhere else."