Roger Federer has a good chance later this year to pass Pete Sampras for most aces in his career. Ivo Karlovic, in turn, is hot on Federer’s heels for No. 4 on the all-time men’s tennis aces list and could pass him at the U.S. Open this week.

You may start hearing more about this leaderboard as Federer and Karlovic keep overtaking former greats and each other. If you do, it’s worth keeping in mind that among trivial sports records, the all-time aces title is a particularly meaningless accomplishment: