Venus Williams made it through to her ninth US Open semi-final after prevailing in three sets against Petra Kvitova.
A two-time winner of the US Open on home soil, American ninth seed Williams overcame Kvitova 6-3 3-6 7-6 (7-2) in an absorbing quarter-final at Flushing Meadows on Tuesday.
There was not much to split Venus and 13th seed Kvitova in New York but the latter's 45 unforced errors compared to 29 proved to be her downfall after two hours, 34 minutes.
It will be an all-American affair in the semis as 37-year-old Williams and Sloane Stephens do battle.
Kvitova outmuscled and overpowered third-seeded Wimbledon champion Garbine Muguruza in the round of 16 and she threatened to do the same against Williams.
The Czech star broke early for a 3-1 lead but that was as good as it got for her in the opening set.
Williams reeled off five successive games to take the lead after Kvitova saved one set point but sent a forehand long on the second.
It was a similar story in the second set as Kvitova capitalised on Williams' serve for a 3-0 advantage before a brief rain delay - leading to the roof being closed - halted her momentum.
Kvitova ensured there was no repeat of her first-set collapse, fending off five break points to level the match and force a decider.
The final set was deserving of a trophy decider as Kvitova and Williams went toe-to-toe, delighting the Arthur Ashe crowd.
There was a break apiece as the match fittingly went to a tie-break, where a double fault and a stray shot sent Williams through to the semis at the year's final grand slam.
Williams  bt Kvitova  6-3 3-6 7-6 (7-2)
Williams - 21/29
Kvitova - 35/45
Williams - 5/7
Kvitova - 8/9
BREAK POINTS WON
Williams - 3/11
Kvitova - 3/4
FIRST SERVE PERCENTAGE
Williams - 59
Kvitova - 56
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Williams - 67/61
Kvitova - 71/47
Williams - 103
Kvitova - 94