Former world number one Andy Murray has been forced to withdraw from the Cincinnati Open due to an abdominal strain.
The 36-year-old - who was recently named in Great Britain's Davis Cup team - was due to face Russian 11th seed Karen Khachanov in his first-round match on Tuesday.
However, Murray's run at last week's Canadian Open was curtailed due to his abdominal concern, and the three-time major winner will not be competing in Cincinnati either.
Murray had got the better of Lorenzo Sonego and Max Purcell in the Canadian Open and was scheduled to meet Jannik Sinner in the last 16, but he announced his withdrawal on the court just before he was due to face the Italian, who ended up winning his first Masters title in Ontario.
As a result, Khachanov - who has only just returned to the ATP Tour himself due to a groin injury - will face a lucky loser in his first-round match, which will mark his first top-level appearance since the French Open.
GB are still represented in the Cincinnati men's singles by Dan Evans and Cameron Norrie, who will take on Lorenzo Musetti and Gael Monfils respectively in their first-round affairs.
