The two young champions, who met as teen-agers, are expected to face off at this year’s U.S. Open.

Jannik Sinner has withdrawn from the U.S. Open mixed doubles event, where he was going to partner Katerina Siniakova, a day after illness forced the world number one to retire five games into his Cin...

Sinner told the crowd: "I'm super sorry to disappoint you. From yesterday I didn't feel great, I thought I would improve but it came up worse. "I tried to come out, to make it at least a small match,...