The promising player will take on Belgian 16th seed David Goffin next in the semis.
Goffin advanced after getting a walkover against Japanese qualifier Yoshihito Nishioka.
The latter couldn't take the court due to illness.
Barty advances, Osaka retires in match against Kenin
Australian Ashleigh Barty edged closer to a return to the top WTA ranking after reaching the WTA semi-finals.
This is a boost for Barty after current number one Naomi Osaka retired with a knee injury.
Barty engineered a superb comeback to beat Maria Sakkari 5-7, 6-2, 6-0.
Meanwhile, Sofia Kenin advanced after seeing a 6-4, 1-6, 2-0 victory over the retiring Osaka.
Osaka bothered by her injury ahead of US Open
With the US Open next, the injury puts a cloud over defending champion Osaka.
"Last year I won the US Open and this year I'm trying to play the US Open. "I don't even really think about winning the tournament. I just want to have the chance to play. If there is one percent chance of me not playing it, that's what's concerning me."
Barty to face Kuznetsova, whereas, Kenin sets up Keys date
French Open champion Barty will face Russian veteran Svetlana Kuznetsova, who beat third seed Karolina Pliskova 3-6, 7-6 (7/2), 6-3 in a tight affair.
"I tried to play every point and stay there. She served amazing," Kuznetsova said.
"I'm in the semis for the first time here. I'm not thinking of the ranking at all. I'm playing one match at a time. If I can win matches, the ranking will take care of itself," said Barty on the WTA rankings.