British light-heavyweight Buatsi made a winning yet underwhelming start to his career under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a majority decision in a tight 10-round fight at the boxing arena.
But the challenger had his moments, delivering effective individual punches in a contest where the techniques never quite clicked, with frequent clinching spoiling the contest.
The scoring judges scored it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my best display but what do champions do? They win," the victor said in the ringside as he was met by boos from the audience.
The British fighter bounced back after his maiden career setback - an epic battle with Callum Smith in February - to claim a 20th pro success.
Various analysts believed the challenger, 31, should have been awarded the decision but the contender suffered the second defeat of his 28-fight professional journey.
Buatsi Claims Win in Slow Encounter
Buatsi's progress has stalled in recent times through contract problems and long spells of inactivity.
Previously predicted as the rising talent of the British fight scene, he now stands trying to fulfil that early promise - perhaps in what feels like a last chance - under fresh management.
He opened tentatively, with the two boxers willing to be aggressive in a calculated initial rounds.
Parker, whose single earlier setback came at the lower weight class against his former opponent in 2022 after suffering a hand injury in the contest, was making just his second bout at light-heavyweight.
By the middle rounds, the underdog had made it competitive, making life awkward for Buatsi, who worked behind a tight guard to barely take the cleaner rounds.
The audience's tolerance wore thin amid frequent holding, with the challenger going down various instances during clinches.
The underdog closed well, but many rounds were challenging to assess. Although, former world champion the boxing analyst - providing analysis for the broadcast network - had it significantly in favor for Parker, awarding Buatsi just a single round.
The victor advances, but with the presence of heavy hitter Benavidez, and Russian star Bivol dominating the weight class, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Tribute Inspires Manchester Derby Fight
In the secondary fight, Arthur beat Bradley Rea by divided decision in a excellent all-Manchester fight to secure the European light-heavyweight championship.
The stadium grew hushed for a profoundly moving memorial ahead of the contest as a bell ceremony rang in memory of local hero Ricky Hatton, who passed away at age 46 in September.
It was the premier televised fight night in the urban center since Hatton's death. As the concluding sound ended, the quiet became a shout of "there's only one Ricky Hatton".
The action inside the ropes reflected the feeling. Arthur was sent to the canvas by a left hook squarely on the face in the second round, getting up unsteadily to his footing on the referee's count.
But the Manchester United-red attire of Arthur soon pressed ahead again. Across the ring, Rea - in competitive blue - was injured early, noticeable damage forming under his eye as the fighters traded hard punches.
Rea, twenty-seven, landed power punches but Arthur, 34, matched the intensity with powerful upward punches as the pace rarely dropped over twelve rounds.
Arthur barely secured the decision with judges scorecards of even score, narrow lead and wider gap, but both fighters were determined and full of heart, all the qualities their hero the legend embodied.
