Viddal Riley missed out on a £10,000 bonus after failing to stop his opponent on the undercard of Amir Khan's clash with Kell Brook.
Riley had been promised the cash bonus by YouTube star KSI, whom Riley coached to victory over Logan Paul in 2019.
But despite dropping Willbeforce Shihepo in the first round, Riley couldn't complete the job and had to settle for a points win.
Having orchestrated KSI's win in his one and only professional fight, Riley turned his attention to his own career.
He made his debut in the paid ranks in 2018 but had fought just four times prior to this weekend.
Riley, 24, had been part of Floyd Mayweather's promotional company but returned to London to sign with new boys on the block BOXXER.
He took on the more experienced Shihepo three hours before Khan and Brook made their walks to the ring.
Riley was the quicker out of the starting blocks as he beat his opponent to the jab.
And he dropped Shihepo with a crunching right hand in the dying embers of the first round, but the veteran rose to beat the count.
Shihepo began to open up in the second round but in doing so left himself vulnerable to Riley's back hand.
Riley was in complete control by the halfway mark but continued to be frustrated in his attempt to record an early finish in the fourth round.
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Londoner Riley had Shihepo pinned in the corner in the fifth session but the Namibian tucked up well on the ropes to fend off the attack.
Shihepo was happy to grapple his way through the final round before the referee handed Riley all six sessions for a score of 60-53.
Earlier, Charlie Schofield lost his English super-middleweight title to Germaine Brown who was given the nod by all three judges by scores of 98-92 (twice) and 98-91.
There were also routine wins for Ibrahim Nadim and for Khan's cousin Abdul as he continued his own professional career.
