Tsvetana Pironkova stuns misfiring Garbine Muguruza at 2020 US Open

Tenth seed Garbine Muguruza was knocked out of the US by Bulgaria's Tsvetana Pironkova - playing her first tournament in three years.

The 32-year-old notched a 7-5, 6-3 win - finishing it with a powerful ace.

"I'm really, really happy that I was able to win this match," said Pironkova afterwards.

She returns to tennis following a hiatus after having her son in April 2018.

"Coming here to the US Open, being my first tournament in three years, was a bit risky, but at the same time I was very excited and motivated to play well on this big stage, and I think that motivation kept me pushing."

Muguruza's frustration was evident, and she demonstrated that at the end of the first set as she smashed her racket on the ground.

"I'm not a type of player that does that [smashing rackets] a lot," Muguruza told the media afterwards.

"I just feel like today out there was a tough first set. I felt I had it in control, then she played very well and took her chances. All of a sudden it was gone."