Serena Williams withdraws from US Open with hamstring not healed

• American not played since picking up injury at Wimbledon
• Raducanu makes smooth progress to second qualifying round

Serena Williams has withdrawn from the US Open, marking another major setback in a difficult season.

Williams, who turns 40 next month, has not competed since she was forced to withdraw from her first-round match at Wimbledon after falling on the slippery grass courts against Aliaksandra Sasnovich, tearing her right hamstring and then leaving the court in tears.