World number three Simona Halep booked her spot in the semi-finals of the Western & Southern Open after beating Anastasia Pavlyuchenkova 7-6 (3), 6-2 in an hour and 41 minutes.
Pavlyuchenkova came on firing on all cylinders as she broke Halep right off the bat before holding serve to take a 2-0 lead.
Pavlyuchenkova continued to remain one step ahead of Halep until the eighth game, where Halep brought the scores level at 4-4 after she broke Pavlyuchenkova.
Halep and Pavlyuchenkova continued to trade blows until they headed into the tiebreak, where Halep, who saved three break points, gained the upper hand and broke the 24-year-old Russian three times en route to clinching a gruelling first set.
The second set proved to be a lot easier for Halep as she raced out to a 3-0 lead, after twice breaking Pavlyuchenkova.
But, Pavlyuchenkova responded by breaking Halep in the fourth and sixth game as she looked to get back into contention. However, it was too little too late as the world number three broke Pavlyuchenkova in the seventh game before converting her fourth match point to advance to the last four.
Halep will face Jelena Jankovic in the semi-finals after she defeated Slovakian qualifier Anna Karolina Schmiedlova 6-4, 6-2.
The second semi-final will feature world number one Serena Williams who will take on 14th seed Elina Svitolina after Williams downed sixth seed Ana Ivanovic 3-6, 6-4, 6-2 and Svitolina trumped seventh seed Lucie Safarova 6-4, 2-6, 6-0.