Defending champion and No.3 seed Tsurenko made it nine successive wins in Acapulco by seeing off Australia's Gavrilova 6-2 6-4.
Despite leading 6-2 5-0, Tsurenko required seven match points to beat Gavrilova and reach back-to-back finals at the Mexican tournament.
"I think it was just getting more and more tough in the second set because her defence was just amazing," Tsurenko, who is yet to drop a set during this year's event, said.
"It was confusing for me and I made a lot of mistakes, probably because I lost some concentration, but I'm really happy I finished 6-4, and not getting to a tiebreak or something like that."
Tsurenko will meet Stefanie Voegele in the final after the Swiss overcame Rebecca Peterson 6-4 7-6 (7-5) as she advanced to her maiden WTA Tour-level decider.