The Frenchman, seeking to extend Arsenal's 62-year unbeaten record in FA Cup ties against their London rivals on Saturday, said he would pick a team that would enjoy the day and play 'the Arsenal way'.
"Yes it is bad news again," Wenger told a news conference when asked about his squad's fitness.
"Bacary Sagna is out because he is ill. He has come to the training ground, but he has a virus, he is weak and cannot play.
"That means we are short in numbers, but not in quality so we will go there and try to play our best. We are not going to sit back and let Chelsea dictate to us."
Arsenal last lost to Chelsea in the FA Cup 2-0 in a third round second replay on Jan. 20, 1947.
"I am not one for the history like that," said Wenger. "This match is about how we play, and how they play, on the day. We are just going there to go for it."
Arsenal will be without first-choice goalkeeper Manuel Almunia (ankle), central defenders Johan Djourou (knee) and William Gallas (knee), full backs Gael Clichy (back) and Sagna (virus) and possibly reserve left back Kieran Gibbs (groin) who was injured during Wednesday's 3-0 Champions League win over Villarreal.
Gibbs is expected to have a fitness test on Saturday at Wembley.
Wenger said his team's greatest challenge would be to contain the threat from Chelsea's in-form Ivorian striker Didier Drogba.
"Didier Drogba is a fighter and we must make sure we contain him. It is one of the keys for us to keep him quiet," Wenger said.
Drogba has scored seven goals in his eight games against Arsenal.
Wenger paid tribute to the achievements of Chelsea manager Guus Hiddink, who has revitalised the side since taking over on a temporary basis in February following the sacking of Brazilian Luiz Felipe Scolari.
"Anyone who has been at the very top level and survived for so long is high quality," he said. "He is very experienced and he has given them belief and strength. They are going to be difficult to beat."
Surprisingly, Wenger said he was not a fan of the new Wembley stadium.
"I have only been there once -- to see the FA Cup final in 2007 between Chelsea and Manchester United -- and I was not too impressed. I loved the old Wembley personally.
"When I was a boy, everyone played on some bad pitches but dreamt of going to play on the perfect grass on the pitch at Wembley. It was part of the history and it was something special. But not now."
