Serena Williams cemented her status as one of the greatest female athletes of all time in tennis by claiming four consecutive major titles from late 2014 through this summer. Although she couldn’t pull off the Grand Slam sweep, losing at the U.S. Open semifinals, expect her endorsements to surge closer to rival Maria Sharapova’s in the coming year—quite an accomplishment for someone who’s 34, an age when many tennis players are past their prime.

This article is part of the 2016 Fortune Crystal Ball, a package of 33 predictions about business, politics and the economy by the writers and editors of Fortune. To see the entire package, click here.