British light heavyweight Buatsi earned a win yet disappointing start to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a competitive ten-round fight at the Co-op Live Arena.
But Parker landed significant shots, connecting with powerful clean blows in a match where the techniques didn't complement each other, with frequent clinching spoiling the action.
The scoring judges had it 96-94 in favor to the winner, with the third a 95-95 draw.
"It wasn't my greatest display but what defines champions? They succeed," the victor said in the ring as he was greeted with negative reactions from the spectators.
The British fighter got back to winning after his initial pro loss - an epic battle with Callum Smith in last winter - to earn a twentieth professional win.
Several boxing experts felt the challenger, thirty-one, should have been awarded the decision but the contender suffered the second setback of his 28-match professional journey.
Buatsi Claims Victory in Dull Encounter
Buatsi's progress has plateaued in recent years through management issues and extended periods of inactivity.
Once tipped as the future of UK boxing, he now is positioned trying to achieve expectations - possibly in what seems like a final roll of the dice - under recent support.
He opened tentatively, with both competitors ready to be aggressive in a cagey early stages.
Parker, whose only previous defeat came at super middleweight against his former opponent in two years ago after damaging his hand mid-fight, was participating in his second fight at light heavyweight.
By the middle rounds, the underdog had stayed in contention, creating difficulties for the favorite, who worked behind a solid defense to narrowly win the better stanzas.
The audience's tolerance wore thin because of regular grabbing, with Parker slipping to the canvas various instances during grappling.
The underdog finished the stronger, but several stanzas were challenging to assess. Nevertheless, former world champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for Parker, giving Buatsi just one round.
The victor progresses, but with the likes of power puncher Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Homage Motivates All-Manchester Fight
In the co-main event, Arthur beat Bradley Rea by close verdict in a excellent Manchester vs Manchester battle to win the European light heavyweight title.
The stadium became quiet for a extremely emotional memorial ahead of the contest as 10 bells sounded in remembrance of local hero Ricky Hatton, who died 46 years old in recently.
It was the first major televised fight night in the location since Hatton's death. As the last bell faded, the stillness became a roar of "only one Hatton".
The fighting during the bout equaled the feeling. Arthur was sent to the canvas by a powerful punch flush on the jaw in the second round, standing uncertainly to his footing on the eight count.
But the red-colored equipment of the fighter soon advanced again. Across the ring, Rea - in opposing blue - was damaged soon, significant bruising appearing under his eye as the fighters exchanged hard punches.
Rea, 27, delivered effective strikes but the champion, thirty-four, responded in kind with effective uppercuts as the intensity seldom decreased over the full distance.
Arthur narrowly won the verdict with scoring tallies of draw, close margin and wider gap, but the two athletes were persistent and brave, exactly what their hero the legend embodied.
