British light heavyweight Buatsi earned a win yet disappointing beginning to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate appeared to earn him a judges' verdict in a competitive 10-round bout at the Manchester venue.
But Parker found success, delivering effective clean blows in a contest where the techniques never quite clicked, with frequent clinching spoiling the contest.
The scoring judges judged it 96-94 for to the winner, with the third a 95-95 draw.
"It wasn't my best showing but how do champions respond? They prevail," the victor commented in the arena as he was faced disapproval from the spectators.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with Callum Smith in last winter - to secure a twentieth professional win.
Various analysts believed Parker, thirty-one, merited the decision but the contender endured the second setback of his 28-bout professional journey.
Buatsi Claims Win in Dull Match
Buatsi's progress has slowed in recent years through promotional disputes and extended periods of inactivity.
Earlier forecast as the future of British boxing, he now finds himself trying to achieve expectations - possibly in what appears to be a ultimate opportunity - under recent support.
He began cautiously, with the two boxers willing to take risks in a cagey opening few rounds.
The challenger, whose sole prior loss came at the lower weight class against John Ryder in 2022 after damaging his hand during the bout, was competing in only his second fight at light heavyweight.
By the fight's midpoint, the underdog had kept it close, causing problems for the favorite, who utilized a solid defense to edge the better stanzas.
The spectators' acceptance decreased during frequent holding, with the challenger going down multiple occasions during clinches.
The underdog closed well, but multiple periods were challenging to assess. Nevertheless, former world champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, giving Buatsi just a single round.
The victor progresses, but with the presence of hard hitter Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - on this evidence - still seems difficult.
Ricky Hatton Homage Motivates Manchester Derby Fight
In the co-main event, Arthur beat Rea by close verdict in a excellent all-Manchester battle to secure the European light heavyweight belt.
The arena fell silent for a profoundly moving homage prior to the bout as ten bells rang in remembrance of the city's native Ricky Hatton, who succumbed aged 46 in September.
It was the premier televised fight night in the urban center since Hatton's death. As the concluding sound ended, the quiet became a shout of "only one Hatton".
The fighting during the bout equaled the sentiment. The eventual winner was knocked down by a left hook flush on the face in the early round, standing uncertainly to his feet on the eight count.
But the red-colored attire of the fighter soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was damaged quickly, significant bruising forming under his orbital area as the duo exchanged powerful shots.
Rea, 27, connected with strong blows but the champion, 34, fought fire with fire with stinging uppercuts as the pace hardly diminished over twelve rounds.
Arthur barely secured the result with scoring tallies of draw, narrow lead and clearer margin, but both fighters were determined and brave, everything their inspiration Hatton represented.
