Ninth-ranked Sakkari, forced to play twice Friday due to rain on Thursday at the WTA and ATP hardcourt event, reached her first final since losing to Pegula last October at Guadalajara.

"It would have been ideal if I could be off the court an hour earlier," Sakkari said. "But at the end I got the win which is what I wanted the most."

Sakkari, who reached her seventh career final, won her only WTA title in 2019 at Rabat.

She will play in Sunday's championship match against the winner of a later semi-final between seventh-ranked American Coco Gauff and 18th-ranked Liudmila Samsonova, the defending champion from Russia.

Pegula, the 2019 Washington champion, was denied her fifth career final but will match her career high of third in the world rankings next week.

Sakkari improved to 5-3 in her career rivalry with Pegula, who won their most recent prior meeting in February's Doha semi-finals.

Sakkari dominated the first set and went up 4-1 in the second but Pegula broke Sakkari in the seventh game of and held to pull level at 4-4.

A double fault handed Pegula a break chance in the ninth game and Sakkari swatted a forehand wide for a 5-4 edge. The American then held to force a third set.

"Things were tricky in the second set," Sakkari said. "In the third, I just tried to stay in the present. I tried to overcome myself and take it as a new challenge."

Sakkari broke early in the third set and again in the final game on a backhand winner to advance after two hours and three minutes.

Sakkari hit 36 winners compared to 29 unforced errors and for 14 of 19 points when she came to the net.

The men's semi-finals were set for Saturday night with US top seed Taylor Fritz, a champion last week in Atlanta, facing Dutchman Tallon Griekspoor and fifth-seeded Grigor Dimitrov of Bulgaria against British ninth seed Daniel Evans.