Nara, the final Japanese representative in the draw, started brightly but it was Cepelova that finished the stronger to run out a 3-6, 6-4, 6-1 winner.
After losing three straight games to drop the first set, Cepelova soon fell a break behind in the second. Rahter than dwell on this setback, the Slovakian used it as a turning point, winning four of the next five games to level the match.
Her dominance continued into the decider a couple of early break giving her stranglehold she would not relinquish.
Since coming through qualifying to reach the third round of Wimbledon, Cepelova's form has been mixed; clay court outings in Gstaad and Bastad both ended in the first round before she fell in the final round of qualifying for the US Open.
In a match that ebbed and flowed for over two and a half hours, the pivotal moment came in the penultimate game. Serving at 3-4, Golubic saved four break points in a titanic game, only to wilt at the fifth time, sending a tied forehand long.
McHale was feeling equally exhausted, barely having the energy to celebrate when she closed out victory a game later. "I think it was a well-fought match. Both of us were producing a high level, but I was really happy I stayed solid in the end because it was only a few points that were the difference."
Siniakova followed up her marathon encounter against Louisa Chirico with a far more straightforward 6-2, 6-4 win over Alison Riske. Zhang was made to work harder, recovering to beat Varvara Lepchenko, 6-7(4), 6-1, 6-3.