A contest that lasted three hours and 12 minutes, finishing just 20 minutes shy of 2:00am local time, began well for Sorribes Tormo, with the No.4 seed taking the opening set.
The Romanian came storming back in the second though and was forcing her opponent all the way back to the advertising curtain with a series of deep shots, while also impressing on her own serve, getting 90 per cent of her first serves in across the set.
Begu ultimately served out to take it 6-3 as the local time went past midnight, but there was plenty more to come as a third set that moved at a glacial pace kept the more dedicated fans in the stands away from their beds.
An hour after the second set had concluded, the score in the third was just 3-2 to Begu after the No.6 seed forced a break against Sorribes Tormo, who was warned with a time violation during the game.
That seemed to be a turning point as one break became two, before the Spaniard broke back to initially frustrate Begu, only for the Romanian to serve out victory at the second time of asking.
She will face Bronzetti in Monday's (AEST) final after the world No.78 also came from behind to win her semi-final with compatriot Jasmine Paolini.
It was a remarkable turnaround considering Paolini won the opening set 6-0, with Bronzetti only winning 33 per cent of points on her own first serve compared to Paolini's 79 per cent on hers.
However, Bronzetti found several more gears in the second set, winning 83 per cent on her first serve this time, and she carried that form into the third, recovering brilliantly to take the match 0-6 6-3 6-3.