British light-heavyweight Buatsi earned a win yet disappointing beginning to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a judges' verdict in a tight ten-round bout at the boxing arena.
But Parker found success, delivering effective single shots in a fight where the approaches never quite clicked, with excessive holding disrupting the fight.
The officials judged it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my best performance but what defines champions? They succeed," Buatsi said in the arena as he was met by disapproval from the spectators.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in last winter - to secure a 20th pro success.
Several boxing experts felt the challenger, 31, should have been awarded the win but the contender endured the second loss of his 28-bout career.
The Champion Earns Victory in Dull Match
The fighter's advancement has slowed in recent years through promotional disputes and considerable time of inactivity.
Previously predicted as the future of British boxing, he now finds himself trying to fulfil that early promise - perhaps in what feels like a last chance - under new promotional backing.
He started carefully, with neither fighter prepared to take risks in a cagey early stages.
Parker, whose single earlier setback came at super-middleweight against his former opponent in two years ago after suffering a hand injury in the contest, was participating in his second fight at light heavyweight.
By the halfway stage, Parker had made it competitive, making life awkward for Buatsi, who worked behind a protective stance to barely take the more effective rounds.
The audience's tolerance decreased amid regular grabbing, with Parker going down various instances during clinches.
Parker ended stronger, but multiple periods were difficult to score. Nevertheless, former world champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, giving Buatsi just only one stanza.
The victor progresses, but with the caliber of heavy hitter David Benavidez, and Russian star Dmitry Bivol ruling the division, the road to world glory - based on this performance - still appears challenging.
Hatton Memorial Inspires Manchester Derby Battle
In the supporting bout, Lyndon Arthur defeated Bradley Rea by close verdict in a excellent all-Manchester battle to capture the continental championship.
The stadium grew hushed for a deeply poignant homage ahead of the contest as ten bells rang in remembrance of local hero Ricky Hatton, who succumbed aged 46 in recently.
It was the premier televised match card in the urban center since the passing of Hatton. As the last bell ended, the stillness became a shout of "there's only one Hatton".
The fighting during the bout reflected the sentiment. The eventual winner was sent to the canvas by a powerful punch flush on the face in the initial stage, standing uncertainly to his footing on the referee's count.
But the red-colored attire of the fighter soon came forward again. On the opposite side, Rea - in opposing blue - was marked up soon, significant bruising developing under his orbital area as the fighters exchanged powerful shots.
The challenger, 27, delivered effective strikes but Arthur, 34, matched the intensity with effective uppercuts as the pace seldom decreased over 12 rounds.
Arthur barely secured the verdict with judges scorecards of draw, narrow lead and wider gap, but both fighters were determined and brave, everything their hero the legend represented.
