Halep will meet Aryna Sabalenka on Saturday for a place in the final after the unseeded Belarusian saved 10 break points en route to a 6-3 6-4 victory over American Madison Keys
World number one Simona Halep pulled double duty at the weather-hit Cincinnati Masters in Ohio on Friday, beating Ashleigh Barty then Lesia Tsurenko to claim a place in the semi-finals.
Halep will meet Aryna Sabalenka on Saturday for a place in the final after the unseeded Belarusian saved 10 break points en route to a 6-3 6-4 victory over American Madison Keys.
The other semi-final will pit Petra Kvitova against unseeded Kiki Bertens of the Netherlands.
After beating Australian Barty 7-5 6-4 earlier in the day, Halep took her winning streak to eight matches with a 6-4 6-1 win over Tsurenko, who had triple break point to take a 5-1 lead in the first set but could not capitalise and saw the match swing away from her.
The top seed was unstoppable once she found her rhythm and confidence, winning 11 of the final 12 games to continue her winning streak stretching back to last week's Rogers Cup.
"It was a tough day," said the Romanian. "I'm really tired but I'm happy that I could win both.
"After I won Montreal, I said that I want to come here to win some more matches, because after winning a title is always the feeling that 'let's do more.'"
Her semi-final opponent Sabalenka had staved off match points in her two previous matches and managed to do it again on Friday, using her big serve to wriggle out of trouble against 13th seeded Keys.
Eighth seed Kvitova recovered from going down an early break in the third set to beat Belgian Elise Mertens 7-5 5-7 6-3.
"Luckily I (had) good second serves, which was very important for me to put it back to the court and play some rallies," said the Czech.
"I really need to play more aggressive. That's how I made those important points."
Bertens trailed 4-1 in the opening set against Ukrainian fifth seed Elina Svitolina but it was one-way traffic once the Dutch player's serve clicked into gear and she closed out the match 6-4 6-3.