US Open semi-finals: Juan Martin del Potro stuns Roger Federer
Argentina's Juan Martin del Potro stunned Roger Federer in four sets to reach the US Open semi-finals.
The 24th seed won 7-5 3-6 7-6 6-4 to reach the last four, thrilling his large contingent of supporters in New York.
He goes on to face top seed Rafael Nadal, who earlier beat Russian teenager Andrey Rublev.
Del Potro's victory means Federer and Nadal will end another year having never played each other at the US Open.
Top seed Nadal is now also guaranteed to keep hold of the number one ranking ahead of Federer.
Madison Keys outplayed Kaia Kanepi to complete an all-American line-up in the US Open women's semi-finals.
The 15th seed won 6-3 6-3 to join Coco Vandeweghe, Venus Williams and Sloane Stephens in the last four.
It is the first time since 1981 that four American women have made the semi-finals in New York, and the first time anywhere since Wimbledon 1985.