Lucie Safarova blasted Czech teammates and friends Lucie Hradecka and Katerina Siniakova for poor sportsmanship in a heated US Open women’s doubles semi-final on Friday, saying it was “sad” for tennis.

Safarova, who was playing alongside another Czech Barbora Strycova, was furious over an incident in her 6-2, 7-5 defeat.

Siniakova hit a ball which deflected off the head of her teammate. Under the rules, the point should have gone to Safarova and Strycova but Hradecka did not acknowledge the ball had hit her.

“Win or lose you should always play fair! Wouldn’t expect that from a friend. Makes me really sad!..#sportsmanship#fairplay#sad,” tweeted Safarova.