Barcelona, powered by the fearsome attacking trio of Lionel Messi, Luis Suarez and Neymar, come into the tie as red-hot favourites and have history in their favour having knocked Arsenal out in 2010 and 2011 as well as beating them in the 2006 Champions League final in Paris.
However, Wenger feels the Gunners stand a genuine chance if they play with patience, discipline and try not to go too gung-ho on Tuesday night.
“It’s our best chance no matter how big the chance is,” The 67-year-old Frenchman said.
We have to take it and have a go at them. I believe in these big games, in the first tie at home, we can’t be stupid.
“Many times we’ve won away and at home we have conceded. We have to find a good balance between defending and attacking.”
Wenger has also backed the rusty Alexis Sanchez to rediscover his form against his former club having netted just once since returning last month from a long injury lay-off.
The Chilean struggled to impress when he came on as a second-half substitute against Hull at the weekend and Wenger has tied that down to his mental state.
“I don’t think he was completely ready to come on. It looked like that but he grows with the game does Sanchez,” he said.
“He has a game based on risk and when he’s completely highly tuned in, it becomes dangerous. Don’t worry about Tuesday, he will be tuned in.”