Lehmann, 37, has previously questioned Almunia's value to Arsene Wenger's team - and there is no love lost between the pair.
But Almunia, 30, beamed: "Now I can really say I'm enjoying myself in London. I feel the No 1 spot is mine.
"I have to grab on to it with all my strength so it doesn't escape me.
"This is my moment and I don't intend to let it go."