Aug 20 (Reuters) - Jessica Pegula ⁠beat Amanda Anisimova 6-4 2-6 7-6(4) to reach ⁠the Cincinnati Open semi-finals on Thursday, with the Americans ‌needing a tiebreak to decide a back-and-forth match.

Anisimova quickly found herself 3-1 down in the first set but clawed her way back, trailing ​5-4 before world number three Pegula ⁠fired off a love hold ⁠to win the set in 34 minutes.

Anisimova began the second ⁠set ‌with more confidence and control, winning her first break point in the second game and quickly ⁠establishinga 3-0 lead before Pegula took a medical ​timeout, resulting ‌in a short delay to the match.

Pegula returned to ⁠the court ​and was swiftly broken before taking the next two games. Although ninth seed Anisimova broke Pegula to win the set, her ⁠control appeared to be faltering heading ​into the decider.

Momentum started to swing Pegula's way as she won three straight games to open the third set, breaking ⁠twice.

Anisimova regained her composure and refused to fade away, erasing a 5-3 deficit to lead 6-5 before Pegula brought the set level and dug deep to win the tiebreak.

Anisimova ​showed great fight throughout the match but ⁠ended the day with 56 unforced errors.

In the semis, Pegula ​faces either Poland's seventh-seeded Iga Swiatek ‌or Kazakhstan second seed ElenaRybakina, ​who are scheduled to play later on Thursday.

(Reporting by Nicole Fernandes in Toronto; Editing by Ken Ferris)