Jack Catterall recovered from a fifth-round knockdown to floor Regis Prograis twice and secure a unanimous points win over the American at Co-Op Live in Manchester.
Chorley's Catterall, who avenged his defeat to Scotland's former world champion Josh Taylor in May, dropped super-lightweight rival Prograis twice in quick succession in the ninth on his way to a convincing win.
The judges scored the contest 117-108, 116-109, 116-109 in Catterall's favour as the 31-year-old won the WBO International belt and moved closer to a shot at a world title.
After four skilful but uneventful opening rounds, Catterall was stunned by a left cross in the fifth, which landed on his temple, and after being caught again with a right hook, his glove touched the floor and he was given a standing count.
Prograis continued to force the issue in the sixth as both fighters let the punches fly in some brutal exchanges.
Catterall was treated for a cut on his hairline at the end of the seventh, but just as the American began to grow in stature, Catterall came storming back into the contest in the ninth.
A brilliantly-timed left cross sent Prograis to the canvas and before he could recover another booming left put him down again.
Both fighters threw caution to the wind, but it was Catterall who finished the stronger, with Prograis looking unsteady on his feet for the last three rounds.
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