By Keith Idec

If boxing fans didn’t know Nieky Holzken before Saturday night, he definitely made them take notice.

Holzken, a late substitute, gave England’s Callum Smith trouble at times in their 12-round semifinal in the World Boxing Super Series’ super middleweight tournament in Nuremberg, Germany. Smith managed to beat the former kickboxing star by unanimous decision – thanks in large part to his stiff, consistent jab – but not before Holzken stalked Smith throughout their bout and landed numerous right hands that often reminded Smith he was in a more difficult fight than the judges’ scores suggested.

Liverpool’s Smith (24-0, 17 KOs) won by large margins on the scorecards of all three judges. Bela Florian scored Smith a 118-110 winner, while Nikolay Sigov and Sergio Silvi both scored it 117-111 for Smith.

The Netherlands’ Holzken (13-1, 10 KOs) was a late replacement for Juergen Braehmer (49-3, 25 KOs). Germany’s Braehmer pulled out of the fight and, in effect, the tournament Monday because of an illness.

Nevertheless, Holzken’s performance was commendable against by far the top opponent of his career, particularly since he took this high-stakes fight on such short notice.

The 27-year-old Smith moved on to the WBSS super middleweight final. He’ll face fellow Brit George Groves in that championship match, scheduled for June 2 at O2 Arena in London. Groves watched Smith beat Holzken from a ringside seat Saturday night.

Groves (28-3, 20 KOs) beat English rival Chris Eubank Jr. (26-2, 20 KOs) by unanimous decision in the first semifinal February 17 in Manchester, England. Groves, who owns the WBA and IBO super middleweight titles, suffered a shoulder injury during his win over Eubank, but he expects to be ready to meet Smith on June 2.

The 34-year-old Holzken took this fight on fight days’ notice. He was already training to fight on Saturday’s undercard when Braehmer informed organizers of the WBSS that he had to withdraw from the fight due to the flu.

Smith was a significant step up in class for Holzken. Before losing to Smith, the former kickboxing world champion had beaten pedestrian opposition or worse since making his pro boxing debut in March 2013.

Holzken also fought for the second time in three weeks. He embraced this quick turnaround because he stopped Ukraine’s Viktor Polyakov (13-3-1, 6 KOs) in the second round February 3 in Helmond, Holzken’s hometown in the Netherlands.

Smith hammered Holzken with a left-uppercut, right-cross combination with just under two minutes left in the 12th round. Holzken came back later in the 12th to crack Smith with two right hands that backed Smith into the ropes.

Smith rocked Holzken with a right uppercut when there was just over a minute to go in the 11th round. By then, Smith had regained control and was on his way toward securing a win that was tougher to secure than anticipated.

There was a brief break at the midway point of the ninth round, so that Holzken’s corner men could fix the tape around his left glove. That tape came loose again later in the ninth, which caused another interruption in the action.

Holzken hit Smith with multiple right hands late in the eighth round. He also landed a right to Smith’s chin after the bell sounded to end the round, which drew a warning from referee Tom Taylor.

Smith’s jab and overhand right helped him fend off Holzken for much of the seventh round. Holzken drilled Smith with an overhand right late in the seventh, though, and followed up with a right hook that made Smith hold him just before the round ended.

Smith managed to have a solid sixth round after Holzken hit him with numerous right hands in the fifth. His activity and jab kept Holzken from firing his right hand in the sixth round, when Smith had some success with his own right hand.

Holzken kept Smith on his back foot throughout the fifth round. The aggressor smashed Smith with several right hooks during a 30-second stretch that began at about the midway mark of the fifth round.

Smith began bleeding from his nose after absorbing those punches in the fifth.

Holzken was the aggressor again in the fourth round. He connected with a solid right hand late in the fourth, but Smith defended himself well when Holzken attempted to follow up.

Holzken connected with an overhand right that woke up Smith with just under a minute to go in the second round. Smith came firing back with a right uppercut that landed flush and knocked Holzken off balance later in the second.

Smith worked well off his jab throughout the first round.

Keith Idec is a senior writer/columnist for BoxingScene.com. He can be reached on Twitter @Idecboxing.