Madrid will host the transformed Davis Cup finals in 2019 and 2020.
Former French Open finalist could cut back on clay court events in 2019.
J-Sizzle shines on B-Day.
Grand Slam king on key to winning a Grand Slam title in age of Big 4.
"They should be fined if they make a big mistake," says US Open champion.
Nick Kyrgios says teammate Frances Tiafoe has "a massive future."
Jack Sock offers simple reason for his doubles succcess.
