Almunia said: "I am very proud. It is a great thing to wear the armband, and it came as a big surprise.
"I am one of the oldest players on the pitch but I have not been here the longest. So it's nice and it means I am doing things well, and that I have the confidence of the boss.
"I will try 100 per cent for Arsenal, and work to help my team in every aspect of the game."
Of the threat from Fenerbahce, last season's beaten Champions League quarter-finalists, Almunia added: "We expect them to put pressure on us, especially in the first 15 minutes, and with their crowd behind them.
"I have a bit more responsibility but there is no extra pressure. I hope I can command my defenders very well to get the points."