UK light-heavyweight Buatsi earned a win yet disappointing beginning to his career under recent management with a points victory over Zach Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a majority decision in a competitive 10-round contest at the Co-op Live Arena.
But the challenger had his moments, landing some telling clean blows in a match where the styles never quite clicked, with constant grabbing disrupting the fight.
Two judges had it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my greatest performance but what defines champions? They win," Buatsi commented in the ringside as he was greeted with negative reactions from the audience.
The British fighter bounced back after his initial pro loss - an epic battle with his previous opponent in February - to claim a 20th pro success.
Some ringside observers thought the challenger, 31, deserved the win but the British boxer suffered the second defeat of his 28-match professional journey.
The Champion Earns Victory in Dull Encounter
The fighter's advancement has plateaued in recent times through promotional disputes and considerable time of inactivity.
Once tipped as the rising talent of the British fight scene, he now finds himself trying to fulfil that early promise - perhaps in what feels like a last chance - under fresh management.
He opened tentatively, with the two boxers willing to overcommit in a tentative initial rounds.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in two years ago after suffering a hand injury in the contest, was competing in only his second bout at light heavyweight.
By the middle rounds, the underdog had stayed in contention, creating difficulties for Buatsi, who worked behind a solid defense to edge the better periods.
The spectators' acceptance wore thin amid regular grabbing, with Parker going down multiple occasions during clinches.
Parker closed well, but many rounds were hard to judge. Nevertheless, ex-champion the boxing analyst - providing analysis for Dazn - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
Buatsi moves on, but with the presence of power puncher David Benavidez, and Russian star Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Hatton Tribute Motivates Manchester Derby Contest
In the secondary fight, Arthur overcame Bradley Rea by divided decision in a outstanding all-Manchester battle to win the continental belt.
The stadium grew hushed for a extremely emotional homage ahead of the contest as a bell ceremony rang in remembrance of local hero Ricky Hatton, who passed away 46 years old in September.
It was the initial significant broadcast fight night in the city since Hatton's passing. As the concluding sound faded, the silence gave way to a roar of "there's just one Ricky Hatton".
The competition inside the ropes matched the sentiment. The eventual winner was knocked down by a powerful punch flush on the face in the initial stage, getting up unsteadily to his position on the count of eight.
But the red-colored shorts of Arthur soon advanced again. Across the ring, the opponent - in opposing blue - was marked up soon, heavy swelling forming under his eye as the fighters exchanged hard punches.
Rea, 27, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the intensity hardly diminished over twelve rounds.
The victor narrowly won the decision with scoring tallies of 114-114, 115-113 and 115-112, but both fighters were relentless and brave, exactly what their inspiration the legend embodied.
