ByBrett Knight

ByBrett Knight,

Forbes Staff.

F

or the past year, tennis has been dominated by the on-court battle between 24-year-old Jannik Sinner of Italy and 22-year-old Carlos Alcaraz of Spain, who have combined for all four Grand Slam singles championships in that span—plus another eight ATP Tour titles along the way. Now, the rivalry is taking a financial turn.