British light heavyweight Buatsi earned a win yet underwhelming debut to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a split decision in a close ten-round fight at the boxing arena.
But the challenger landed significant shots, connecting with powerful clean blows in a contest where the approaches didn't complement each other, with frequent clinching spoiling the fight.
The scoring judges judged it 96-94 to the winner, with the third a 95-95.
"It wasn't my finest display but what do champions do? They succeed," the victor stated in the arena as he was greeted with boos from the crowd.
The British fighter got back to winning after his first professional defeat - an memorable fight with Callum Smith in February - to secure a 20th pro success.
Various analysts believed Parker, 31, should have been awarded the victory but the Derbyshire fighter experienced the second defeat of his 28-match professional journey.
The Champion Earns Win in Dull Affair
The fighter's advancement has stalled in the past few years through management issues and long spells of inactivity.
Once tipped as the next star of UK boxing, he now stands trying to realize his potential - perhaps in what appears to be a last chance - under recent support.
He opened tentatively, with both competitors willing to take risks in a tentative early stages.
Parker, whose only previous defeat came at super-middleweight against John Ryder in 2022 after breaking his hand during the bout, was competing in only his second fight at the higher weight class.
By the fight's midpoint, the underdog had made it competitive, causing problems for the favorite, who worked behind a solid defense to edge the better rounds.
The audience's tolerance decreased because of regular grabbing, with the challenger slipping to the canvas various instances during clinches.
Parker ended stronger, but multiple periods were hard to judge. However, ex-champion the boxing analyst - commentating on Dazn - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
The victor advances, but with the likes of power puncher David Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - judging by this showing - still seems difficult.
Hatton Memorial Inspires All-Manchester Contest
In the secondary fight, Lyndon Arthur overcame Rea by split-decision in a outstanding Manchester vs Manchester fight to capture the European light heavyweight championship.
The venue fell silent for a profoundly moving tribute ahead of the contest as 10 bells rang in remembrance of local hero Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast match card in the city since Hatton's death. As the last bell ended, the stillness became a shout of "only one Ricky Hatton".
The action during the bout equaled the emotion. The eventual winner was sent to the canvas by a powerful punch flush on the jaw in the initial stage, standing uncertainly to his position on the count of eight.
But the traditional red attire of Arthur soon advanced again. On the opposite side, Rea - in rival City blue - was injured soon, heavy swelling forming under his eye as the fighters landed powerful shots.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, fought fire with fire with stinging uppercuts as the pace hardly diminished over twelve rounds.
The victor edged the decision with judges scorecards of even score, 115-113 and clearer margin, but each competitor were persistent and full of heart, everything their inspiration the legend embodied.
