AN AMERICAN tennis player has sent cries of anguish echoing through Wimbledon after she suffered a horrific on-court injury on Thursday.

US star Bethanie Mattek-Sands was in the third and final set of her second-round singles match against Romanian Sorana Cirstea when her leg buckled and she fell to the ground in pain.

The 32-year-old lay on her side clutching her right knee for a few moments before she began to scream in agony.

"Help me! Help me please! I need help please! F***!" she howled, as the horror incident played out on live TV.

The crowd looked on stunned as her opponent jumped the net to help her out. Cirstea was later seen in tears.

Mattek-Sands' husband Justin Sands tended to her as she lay on the turf of court 17, butit took the medics so long to tend to her opponent, according to The Mirror.

"I went over and saw her knee out and turned around and told them to bring a stretcher because I think everyone froze," she said.

"It was heartbreaking because she went into shock and it took a while until the medical team was there … Her knee was in a very weird position. I have never seen anything like this except in the movies. I panicked a little bit as well and called for help but no one was coming and I tried to comfort her as much as I could but you could feel the pain.

Bethanie Mattek-Sands in agony as medics tend to her. Picture: David Ramos/Getty Images

"She went into shock and saying 'Sorana