British light-heavyweight Buatsi earned a win yet disappointing beginning to life under recent management with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a tight ten-round contest at the boxing arena.
But Parker landed significant shots, delivering effective clean blows in a contest where the techniques never quite clicked, with excessive holding marring the contest.
The scoring judges scored it 96-94 to Buatsi, with the final judge a 95-95.
"It wasn't my greatest showing but how do champions respond? They win," the victor stated in the ring as he was met by boos from the crowd.
The Londoner bounced back after his maiden career setback - an memorable fight with Callum Smith in last winter - to earn a 20th pro success.
Several boxing experts felt the challenger, 31, deserved the win but the British boxer suffered the second setback of his 28-fight professional journey.
Buatsi Secures Triumph in Slow Affair
Buatsi's progress has plateaued in the past few years through management issues and long spells of inactivity.
Previously predicted as the next star of UK boxing, he now stands trying to fulfil that early promise - possibly in what seems like a last chance - under new promotional backing.
He opened tentatively, with neither fighter willing to take risks in a calculated early stages.
Parker, whose single earlier setback came at super-middleweight against his former opponent in 2022 after damaging his hand during the bout, was making just his second bout at the higher weight class.
By the fight's midpoint, the underdog had made it competitive, creating difficulties for Buatsi, who operated with a protective stance to edge the cleaner rounds.
The spectators' acceptance diminished amid constant clinching, with Parker slipping to the canvas multiple occasions during clinches.
Parker closed well, but many rounds were difficult to score. Although, previous titleholder the boxing analyst - providing analysis for Dazn - had it strongly leaning for the challenger, awarding Buatsi just a single round.
The victor advances, but with the likes of power puncher Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the journey to titles - on this evidence - still appears challenging.
Hatton Tribute Inspires All-Manchester Battle
In the secondary fight, Arthur beat Bradley Rea by close verdict in a excellent all-Manchester battle to win the European light-heavyweight belt.
The stadium fell silent for a deeply poignant homage prior to the bout as a bell ceremony sounded in honor of local hero Ricky Hatton, who died 46 years old in recently.
It was the first major televised match card in the city since Hatton's death. As the last bell disappeared, the stillness became a shout of "there's only one Ricky Hatton".
The competition inside the ropes reflected the emotion. The eventual winner was floored by a left hook squarely on the chin in the second round, getting up unsteadily to his feet on the eight count.
But the red-colored equipment of the fighter soon pressed ahead again. From the other corner, Rea - in opposing blue - was damaged early, heavy swelling appearing under his eye as the pair exchanged hard punches.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace seldom decreased over twelve rounds.
The victor edged the verdict with official scores of even score, 115-113 and clearer margin, but each competitor were relentless and courageous, all the qualities their idol Hatton stood for.
