The Gunners dropped two points at home to Everton this week.
But Mertesacker says: "Chelsea and Tottenham play against each other and Everton have tough games as well. It is absolutely tight. Hopefully for us we can win our important games, especially when we look at Saturday away. That's the next target. We go there and want the three points.
"We are in an interesting position and we came back very strong. We responded well in the last couple of weeks. That is our way and we are still on a good run."