He said: "Every game is big now but that's how you like it as a player. You want to be competing for trophies. If you have three games every week, it shows you're doing something right."
Van der Sar also believes United have the upper hand over Arsenal in the title race.
He added: "Things keep changing. We were five points behind a couple of weeks ago and thought it would be difficult because you're relying on them dropping points.
"Thankfully for us they've drawn their last two games and we're right back in there."