WBC Diamond titlist Callum Smith was surprisingly extended 12 rounds by Nieky Holzken in their World Boxing Super Series semi-final Saturday in Nuremberg. The latter, a successful Dutch kickboxer who had amassed 13 wins in professional boxing, was upgraded from reserve to main event when Juergen Braehmer pulled out only this week.

Smith had won 17 of his 23 previous contests by knockout but Holzken took him the distance. He did not derail the Liverpudlian’s progression to the final.

Smith won the decision unanimously. Bela Florian scored 118-110 and Nikolay Sigov and Sergio Silvi both scored 117-111, all for Callum Smith.

Smith has won a place in the World Boxing Super Series final against WBA super-middleweight champion George Groves, a contest pencilled in for June 2 at the O2 Arena in London. Groves though dislocated his shoulder as he defeated Chris Eubank Jr, so that date could be subject to change.

Callum Smith

On the undercard heavyweight Filip Hrgovic outscored Sean Turner over eight rounds.

Dmitrii Chudinov also outpointed Siarhei Khamitski in an eight-rounder.