The tournament was pushed into an extra day despite an earlier start time on a Sunday that saw Niculescu shock top seed Agnieszka Radwanska in one semi-final.
Pole Radwanska imploded in a decider, losing??5-7 6-4 6-0, leaving Romanian Niculescu to take on Croatia’s Konjuh for the top prize.
The 17-year-old was busy on Sunday, completing a 6-2 6-2 quarter-final victory over??Sachia Vickery to set up a last-four meeting with fifth seed Alison Riske.
A stop-start match went the way of Konjuh, who eventually came through 6-3 6-4 after 6pm.