No.4 seed Sergiy reached the second round of the Open de Rennes challenger on Wednesday with a 6-3, 5-7, 6-2 victory over world no.411 Remi Boutillier in one hour and 40 minutes.
Stako broke in the fourth game of the first set to move ahead, but the French qualifier responded by breaking in the 12th game of the second set to level the contest.
The Kiev native, who is currently ranked no.111st in the ATP rankings, regained the momentum in the decider, and with two breaks of serve - in the first and third games - sealed the win.
Stats: aces (6-3), double faults (5-0), total points won (93-80).
Sergiy will next face either Blaz Kavcic (SLO) or Jurgen Zopp (EST).
In the doubles competition, Stako and Czech Roman Jebavy eliminated no.3 seeds Sergio Galdos (PER) and Fabricio Neis (BRA) recording a 6-4, 6-3 win. They will play against Thai duo, Sanchai and Sonchat Ratiwatana, in the quarters.