ORDER OF PLAY
Play starts at 1pm
J PEGULA (USA) v A KALINSKAYA (RUS)
C GIORGI (ITA) v C MCNALLY (USA)
JOHN HARRIS COURT
After Two Men's Doubles matches
C GAUFF (USA) / C MCNALLY (USA) v M SANCHEZ (USA) / F STOLLAR (HUN) 
Camila Giorgi and Catherine McNally are meeting for the first time, as are Jessica Pegula and Anna Kalinskaya.
Giorgi and McNally have both dropped one set en route to Saturday's semifinal, while No.4 seed Hsieh Su-Wei was the only seed beaten by either player this week.
Pegula has also lost just one set this week, while Kalinskaya was taken the distance by both Monica Puig and Kristina Mladenovic.
Pegula accounted for sixth seed Katarina Siniakova, while Kalinskaya beat eighth seed Puig in the second round.
While seven of the eight second round matches went the distance, just one of the quarterfinals were determined by three sets.
Pegula and McNally are the first Americans in the last four in Washington in three years, since Pegula herself, alongside Lauren Davis, made the 2016 semifinals.
Sloane Stephens was the last home winner of the event, back in 2015.
Kalinskaya is seeking to become the third successive Russian champion, following previous wins for Ekaterina Makarova and Svetlana Kuznetsova. Russian players have won four of the eight holdings of the event.