UK light-heavyweight Buatsi made a winning yet underwhelming beginning to his career under recent management with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a competitive ten-round bout at the Co-op Live Arena.
But the challenger found success, connecting with powerful single shots in a match where the techniques never quite clicked, with excessive holding spoiling the action.
Two judges judged it 96-94 to Buatsi, with the remaining official a even score.
"It wasn't my best performance but what do champions do? They win," Buatsi commented in the arena as he was met by negative reactions from the crowd.
The Londoner bounced back after his first professional defeat - an epic battle with his previous opponent in last winter - to earn a 20th career victory.
Several boxing experts felt the challenger, thirty-one, should have been awarded the victory but the Derbyshire fighter endured the second setback of his 28-match professional journey.
Buatsi Claims Victory in Slow Encounter
Buatsi's progress has plateaued in the past few years through contract problems and long spells of inactivity.
Previously predicted as the next star of UK boxing, he now stands trying to fulfil that early promise - maybe in what feels like a final roll of the dice - under fresh management.
He opened tentatively, with both competitors ready to be aggressive in a tentative opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in 2022 after damaging his hand mid-fight, was participating in his second appearance at the higher weight class.
By the middle rounds, the underdog had stayed in contention, making life awkward for Buatsi, who utilized a protective stance to edge the better stanzas.
The crowd's patience decreased because of frequent holding, with the challenger slipping to the canvas various instances during clinches.
The underdog closed well, but many rounds were challenging to assess. Nevertheless, previous titleholder the boxing analyst - working with the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just a single round.
The victor moves on, but with the likes of heavy hitter Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - judging by this showing - still looks steep.
Hatton Memorial Fuels Manchester Derby Contest
In the supporting bout, Lyndon Arthur overcame Rea by close verdict in a outstanding all-Manchester contest to win the European light heavyweight title.
The stadium fell silent for a deeply poignant memorial ahead of the contest as 10 bells tolled in remembrance of the city's native Hatton, who passed away aged 46 in September.
It was the initial significant broadcast boxing event in the city since Hatton's passing. As the last bell faded, the silence became a shout of "only one Hatton".
The fighting during the bout reflected the sentiment. Arthur was sent to the canvas by a powerful punch directly to 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. Across the ring, the opponent - in opposing blue - was marked up soon, noticeable damage developing under his eye as the pair exchanged punishing blows.
The challenger, 27, connected with strong blows but Arthur, thirty-four, fought fire with fire with powerful upward punches as the pace rarely dropped over the full distance.
Arthur edged the decision with official scores of 114-114, 115-113 and wider gap, but each competitor were relentless and courageous, exactly what their idol Hatton embodied.
