Coco Gauff's US Open title defence is over after she was beaten by Emma Navarro in the fourth round in New York.

Third seed Gauff produced a disjointed performance to lose 3-6 6-4 3-6 to fellow American and 13th seed Navarro.

Gauff hit 19 double faults, with three in the final game helping secure victory for Navarro and send her into a first US Open quarter-final.

Navarros victory ends Gauffs bid to become the first woman to defend the US Open title since Serena Williams in 2014.

It also makes the 23-year-old the youngest American woman to make the quarter-finals at both Wimbledon and the US Open in the same year since Williams in 2004.

"I lost in the first round the last two years and now to be making the quarter-finals is pretty insane," said Navarro.

"This is the city I was born in and it feels so special to be playing here. Coco is an amazing player.

"I have a ton of respect for her and I know she's going to come back here and win this thing again."