This week's #TennisToughCall. Which 20-Year-Old will finish the year ranked higher – Alexander Zverev or Jelena Ostapenko? READ AND VOTE NOW!

Every week Tennis Channel and Tennis.com will be introducing a Tough Call around a thought provoking topic - and our panel of experts will chime in both on-air and online. Be sure to join the discussion, weigh in on our polls, or comment on Facebook and Tw