Emma Raducanu is out of the Slovenia Open after a disappointing defeat by Germany’s Anna-Lena Friedsam in Portoroz.
The British number one was top seed at the event but fell to a 7-5 0-6 6-3 loss in the second round.
Raducanu was leading 5-3 in the first set against qualifier Friedsam, ranked 213 in the world, before appearing to look uncomfortable in her movement.
Her left thigh was strapped following a medical timeout after the first set.
The Briton cruised through the second set without dropping a game but fell short in the decider.
Raducanu’s ranking plummeted to 83 following her recent first-round exit at the US Open, but she will retain her position as British number one after Harriet Dart failed to reach the second round.
Britain’s Jodie Burrage was also beaten in the second round, losing 7-5 6-1 to Katerina Siniakova, but Katie Swan reached the first WTA Tour quarter-final of her career with a 7-6 (7-5) 6-2 victory over Anastasia Gasanova at the Chennai Open.