The two teams face off tomorrow.
Wenger said: "The gap is not big at the moment. We know that our home form will be absolutely vital and we just come home from West Brom frustrated because we lost two points. We know it puts us under even more pressure to deliver a big result tomorrow.
"We've played Chelsea many times and the results were always tight, apart from at home last year, we beat them 3-0. We've played them many times and they were always big battles. Chelsea are coming back into good form. They've been consistent recently so it's a big challenge for us tomorrow."
Wenger took issue with reporters claiming today that Chelsea perform more consistently.
"You're a bit harsh with us because we made 75 points last year and you need some consistency to do that, and we won the FA Cup against a strong team. Just to get to the final of the FA Cup, you need to be consistent. I believe that the Premier League is very even and very difficult for everybody. The target in 2018 is to win every single game, and the next one is Chelsea."