Simona Halep recovered from a slow start to beat Lesia Tsurenko in straight sets on Friday and advance to the semi-finals of the Cincinnati Masters. 

Halep gave up breaks in each of her first two service games to find herself 1-4 down against Tsurenko at the WTA Premier 5 event in Ohio.

The world number one saved four break points in the sixth game to finally hold.

And the determination of the Romanian turned the match on its head, Halep reeling off the next 10 games to take complete control of the contest.

Tsurenko did manage to break in the sixth game of the second set to avoid suffering a bagel, but it was no more than a token gesture from the beleaguered Ukrainian.

Halep had already beaten Ashleigh Barty earlier in the day to complete a third-round match that had been delayed due to rain.

And the Wimbledon champion was satisfied with her efforts in managing the additional workload. 

"I think I changed the game, I lost the first games without really thinking," she said in an on-court interview. "To play two matches in the same day and to win both of them, I'm really happy."

"For everybody it was the same, it was a tough day, but I'll not complain."

A beaten finalist in Cincinnati in 2015 and 2017, Halep will take on 13th seed Madison Keys or Aryna Sabalenka in the last four.