Out-of-favour Lehmann plunged his Gunners future into doubt on Tuesday by revealing he felt "humiliated" by his ongoing omission from the side.
The 37-year-old keeper was also disparaging of Almunia in an interview with German pay-tv station Premiere, declaring: "Almunia hasn't shown that he can win us matches just yet.
"I have been through this situation once and know how the other keeper is situated mentally. I can't imagine he will handle this."
But Almunia, who has tightened his grip on the number one jersey with a run of six clean sheets in the last seven matches, has taken the outburst in his stride.
"I'm not worried about that (Lehmann's comments). Nothing can disturb me and nothing can turn my mind on to other things," said the 30-year-old.
"I don't want turn my mind to other things. I only want to win games for Arsenal. I don't care about any other aspect.
"I will stay positive. The goalkeeping position is a difficult position.
"I've been here almost three years without playing in the league. It's normal for people to assess the situation.
"I forget the past now I'm playing. It's not a problem. I don't care about pressure. I only want to play well.
"If I read the papers and listen to what other people say about me and all these things, then I'd will turn crazy. I don't want that.
"When I'm playing well I honestly don't mind other things that are happening.
"Maybe if I was playing badly I would be more worried. But now for me life is fantastic and I want to take my chance."