Back in the day there were.
Ana and Jelena were once #1 and #2 in the world; it seemed like Serbia would be the next tennis powerhouse with Novak on the men's side.
Not to mention Ana and Jelena hated each other during their peaks so their fans took notice.
How the mighty have fallen though. I still don't like Ana though. I can't forgive her for all her Fed Cup 'injuries'.