By HOWARD FENDRICH
AP Tennis Writer
Fifth-ranked Sofia Kenin has pulled out of the U.S. Open because she recently tested positive for COVID-19. Kenin says she has received a vaccine for the illness. She announced what she called “disappointing news” on social media. Kenin is a 22-year-old American who won the 2020 Australian Open and was the runner-up at the French Open later last year. Her best showing at the U.S. Open was a fourth-round finish last year. Serena and Venus Williams also withdrew from the year’s last Grand Slam tournament on Wednesday, as did 2016 Wimbledon runner-up Milos Raonic.