SERENA WILLIAMS WITHDRAWS FROM CINCINNATI OPEN(WHATS WRONG?)

Serena Williams was knocked out of the Olympic Games tennis tournamentin the third roundSerena Williams could lose her world number one ranking this week after withdrawing from the Cincinnati Open because of a shoulder injury.Second seed Angelique Kerber will replaceWilliams at the top of the standings if she wins the tournament.Williams, 34, had last week accepted a wildcard to defend her title after playing at the Olympic Games in Rio."My shoulder inflammation continues to bea challenge, but I am anxious to return as soon as possible," she said.The American withdrew following a practice session on Monday.Williams has been ranked world number one for 183 consecutive weeks, and 306 intotal.She was knocked out of the Olympics in the third round by Ukrainian Elina Svitolina,and was beaten in the doubles with sister Venus in the first round - their first defeat in 16 Olympic matches together.The US Open, the final Grand Slam of the year, begins on 29 August.