The Filipino fighter came into the fight with huge confidence after a unanimous decision upset win over Cuban star Guillermo Rigondeaux earlier this year.
He immediately displayed his confidence by dropping Potapov in the opening round with a grazing left hook.
The 25-year-old Astrolabio sent the tough Potapov on one knee with a left hook in the fifth round for his second knockdown.
After landing some vicious punches, Astrolabio connected with a solid right hook that sent Potapov on his knees. Potapov didn’t bother to stand up and was counted out by referee Robert Hoyle in the 1:26 mark of the sixth.
Astrolabio, the No. 6 ranked bantamweight by the IBF, won his sixth straight fight and improved to 18-3 with 16 knockouts, while the 32-year-old Potapov fell to 23-3-1 with 11 knockouts.
Astrolabio is now the mandatory challenger of the IBF bantamweight that is currently around the waist of undisputed bantamweight world champion Naoya Inoue.