British light-heavyweight Buatsi earned a win yet disappointing debut to his career under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a judges' verdict in a close ten-round fight at the Co-op Live Arena.
But the challenger landed significant shots, connecting with powerful single shots in a fight where the techniques never quite clicked, with excessive holding disrupting the contest.
Two judges judged it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my finest display but what defines champions? They succeed," Buatsi said in the arena as he was greeted with negative reactions from the crowd.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to earn a 20th pro success.
Various analysts felt Parker, thirty-one, deserved the decision but the British boxer experienced the second defeat of his 28-fight professional journey.
The Champion Secures Victory in Dull Affair
Buatsi's progress has plateaued in the past few years through contract problems and extended periods of inactivity.
Once tipped as the next star of UK boxing, he now finds himself trying to achieve expectations - perhaps in what appears to be a ultimate opportunity - under recent support.
He opened tentatively, with the two boxers willing to take risks in a tentative opening few rounds.
Parker, whose only previous defeat came at super-middleweight against his former opponent in 2022 after damaging his hand during the bout, was making just his second fight at the higher weight class.
By the middle rounds, Parker had kept it close, creating difficulties for Buatsi, who operated with a protective stance to narrowly win the better periods.
The crowd's patience decreased amid constant clinching, with Parker going down multiple occasions during grappling.
The underdog closed well, but multiple periods were challenging to assess. Nevertheless, ex-champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
The victor progresses, but with the likes of power puncher Benavidez, and Russian star Bivol ruling the division, the road to world glory - judging by this showing - still appears challenging.
Ricky Hatton Homage Motivates Local Rivalry Contest
In the co-main event, Lyndon Arthur overcame Bradley Rea by split-decision in a terrific all-Manchester fight to win the European light-heavyweight belt.
The venue became quiet for a deeply poignant memorial ahead of the contest as ten bells tolled in memory of local hero Ricky Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast boxing event in the location since Hatton's death. As the last bell ended, the stillness became a roar of "only one Ricky Hatton".
The action during the bout equaled the sentiment. The eventual winner was knocked down by a left hook flush on the jaw in the initial stage, getting up unsteadily to his footing on the referee's count.
But the traditional red attire of the fighter soon came forward again. Across the ring, Rea - in rival City blue - was damaged quickly, significant bruising forming under his face as the fighters landed punishing blows.
Rea, 27, landed power punches but Arthur, 34, matched the intensity with stinging uppercuts as the intensity hardly diminished over the full distance.
Arthur barely secured the decision with judges scorecards of draw, narrow lead and wider gap, but the two athletes were persistent and brave, exactly what their inspiration the legend stood for.
