The London rivals meet at The Emirates on Sunday.
Mikel said: "Arsenal is going to be a massive game - and we have to make sure we win. We have to make sure we keep the distance at the top. If we do this towards the end of the season, this is going to count.
"If we beat Arsenal, 11 points would be a massive gap over them. But don't forget last season, at some point we were 12 points ahead and we lost it so we just have to keep our concentration and make sure we keep playing well.
"I think this period is a really massive period for Chelsea. Especially with us having the African players going away in January.
"We just have to make sure that we pick up the points now. Even if I go away, I just hope that things keep going well for the team.
"We have to make sure right now that we keep helping the team win games - and I think this period will really determine who is going to win the league."