Like boulter

American Jessica Pegula: Marta Kostyuk of Ukraine stunned top seed American Jessica Pegula 7-6(4), 6-1 in the semifinals of the San Diego Open.

The 21-year-old Ukrainian overcame a 5-1 deficit in the first set to surge past the World No.5 in 1 hour and 35 minutes and will face Katie Boulter for the title on Sunday.

Pegula led the head-to-head 2-0 and looked primed to maintain her perfect record over Kostyuk. Down 5-1, Kostyuk increased her aggression and turned the tables quickly.