The 27-year-old has made just 26 appearances in five years with Fulham.
He said: "I will make Maarten, or whoever is in front of me, work for their job.
"Just because Mark Schwarzer was No1 for all those years does not mean that I was easing off and letting him be there. Every day I have the chance to show the boss what I am capable of.
"When you are fighting to get into the first team you have got to really battle to make it."
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