British light-heavyweight Buatsi earned a win yet disappointing beginning to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a split decision in a tight ten-round bout at the boxing arena.
But the challenger had his moments, connecting with powerful clean blows in a contest where the techniques didn't complement each other, with frequent clinching disrupting the action.
The scoring judges judged it 96-94 for to the winner, with the third a 95-95.
"It wasn't my best display but how do champions respond? They win," Buatsi commented in the ring as he was greeted with negative reactions from the audience.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with his previous opponent in last winter - to claim a twentieth professional win.
Several boxing experts felt the challenger, thirty-one, deserved the decision but the contender experienced the second defeat of his 28-fight career.
The Champion Claims Win in Slow Match
The fighter's advancement has stalled in the past few years through management issues and considerable time of inactivity.
Once tipped as the rising talent of British boxing, he now is positioned trying to fulfil that early promise - possibly in what seems like a last chance - under fresh management.
He started carefully, with neither fighter prepared to take risks in a tentative early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand mid-fight, was making just his second appearance at the higher weight class.
By the halfway stage, Parker had stayed in contention, causing problems for Buatsi, who worked behind a tight guard to barely take the more effective rounds.
The crowd's patience decreased amid frequent holding, with the challenger going down various instances during close exchanges.
The underdog closed well, but many rounds were hard to judge. Nevertheless, previous titleholder the boxing analyst - providing analysis for Dazn - had it particularly wide for Parker, awarding Buatsi just a single round.
The victor advances, but with the likes of power puncher David Benavidez, and Russian champion Bivol leading the category, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Tribute Fuels Local Rivalry Fight
In the secondary fight, Lyndon Arthur beat Bradley Rea by close verdict in a excellent all-Manchester contest to capture the continental championship.
The arena fell silent for a deeply poignant tribute before the fight as a bell ceremony rang in memory of the city's native Hatton, who succumbed 46 years old in September.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the concluding sound ended, the quiet became a chant of "there's only one Hatton".
The competition within the ring equaled the sentiment. The eventual winner was sent to the canvas by a left hook flush on the face in the initial stage, standing uncertainly to his feet on the eight count.
But the Manchester United-red equipment of the fighter soon pressed ahead again. From the other corner, the opponent - in opposing blue - was damaged soon, heavy swelling developing under his face as the duo landed hard punches.
Rea, twenty-seven, landed power punches but the champion, thirty-four, matched the intensity with powerful upward punches as the intensity hardly diminished over twelve rounds.
The victor barely secured the verdict with scoring tallies of draw, 115-113 and wider gap, but both fighters were persistent and courageous, all the qualities their inspiration the legend stood for.
