The boss - who has been in charge since 1996 - admits he still has to put on a front to make sure the players are all feeling confident ahead games.
Arsenal are third in the Premier League - on course for another top four finish - with eight games to go.
And this weekend's clash with could go a long way to deciding who gets into next year's Champions League.
And Wenger will be hoping his players go into the game with full tanks.
“Everybody is different and approaches a matchday differently, but I always try to be confident,” Wenger told Arsenal Player.
“I’m always confident that my team will do well and I want to show that.
“But you never know exactly the mental energy that will be in the team during the game, nor the physical energy that will be in everybody that day. Why? Because we are all human beings and don’t wake up every day in exactly the same state.
"That goes for each of the players as well, so if you multiply by 18, it shows you the uncertainty that can create. So I’m confident but also a bit uncertain and curious as to what kind of mental and physical energy will be in the tank for the team.
"I make sure that everybody around the team fills that tank as much as we can. Of course there is a certainty about the quality of my players but an uncertainty about the energy level that will be available on the day of the game.”