Wenger sees tomorrow's top-of-the-table clash with Chelsea as the defining moment in their season.
He warned: "We cannot be considered a young team any more. We have to show we have grown up.
"There comes a period for every team when they have to show their strengths. For us, this moment has arrived. Chelsea will be one of our biggest tests and we have to prove we are ready, focused and confident.
"We have to win all our home games against the title fighters. If we do that, we can put ourselves in a very strong position."
Wenger is haunted by memories of last season's 4-1 home defeat to Guus Hiddink's Chelsea.
He added: "That result hurt us very much and was difficult to swallow. It was the nightmare week of last season."