Twenty-one match alerts were received during the first quarter of 2019.
One goal drives 23-time Grand Slam champion.
Janko Tipsarevic is sharing his knowledge in a unique online course.
Foot injury forces Isner out, Stevie Johnson is top seed.
The 2020 Olympic Games will no longer feature a best-of-five set men's singles final.
The Russian has not played since last September.
The American could miss more than a month, depending on what further tests reveal.
