Daniel Altmaier was frustrated by losing his serve to Tommy Paul at a crucial time during their Hamburg Open quarterfinal in Germany.

A whole new set of tennis rules will be tested by the ATP Tour during a new season-ending tournament for the top 21-and-under players in Milan in November.

Last year, when Novak Djokovic brought in Andy Murray as coach, his singular goal was clear: claim a 25th Grand Slam and surpass Margaret Court’s legendary tally. That dream faltered after six months, ...

Laver Cup Day 2: Federer tops Krygios; Nadal splits; Europe leads 7-5 ...