British light-heavyweight Buatsi earned a win yet disappointing debut to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output likely gained him a majority decision in a competitive ten-round contest at the boxing arena.
But Parker found success, landing some telling individual punches in a match where the approaches failed to mesh, with constant grabbing marring the contest.
The officials judged it 96-94 for to the winner, with the third a 95-95.
"It wasn't my finest display but how do champions respond? They prevail," the victor stated in the ringside as he was greeted with boos from the crowd.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in last winter - to claim a 20th career victory.
Some ringside observers thought Parker, 31, merited the victory but the contender endured the second defeat of his 28-match career.
The Champion Secures Victory in Slow Match
His career development has plateaued in recent times through management issues and extended periods of inactivity.
Earlier forecast as the future of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what appears to be a last chance - under fresh management.
He opened tentatively, with both competitors willing to be aggressive in a cagey opening few rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in 2022 after damaging his hand in the contest, was making just his second bout at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for the favorite, who operated with a solid defense to edge the cleaner stanzas.
The audience's tolerance wore thin during frequent holding, with Parker slipping to the canvas various instances during grappling.
The underdog ended stronger, but many rounds were challenging to assess. Although, ex-champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, giving Buatsi just one round.
The victor advances, but with the presence of heavy hitter Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Memorial Motivates All-Manchester Contest
In the secondary fight, Arthur beat Rea by divided decision in a outstanding Manchester vs Manchester battle to capture the continental championship.
The arena fell silent for a deeply poignant tribute ahead of the contest as ten bells sounded in honor of local hero Ricky Hatton, who passed away 46 years old in September.
It was the first major televised fight night in the urban center since Hatton's passing. As the final chime faded, the stillness gave way to a chant of "there's only one Hatton".
The action during the bout reflected the feeling. Arthur was sent to the canvas by a left hook flush on the jaw in the early round, getting up unsteadily to his position on the count of eight.
But the traditional red shorts of the fighter soon pressed ahead again. Across the ring, the opponent - in competitive blue - was marked up quickly, noticeable damage appearing under his face as the pair traded powerful shots.
The challenger, 27, landed power punches but Arthur, thirty-four, fought fire with fire with powerful upward punches as the action hardly diminished over 12 rounds.
The victor edged the result with judges scorecards of even score, narrow lead and wider gap, but the two athletes were persistent and full of heart, exactly what their idol the legend represented.
