British light-heavyweight Buatsi made a winning yet disappointing start to life under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a close ten-round fight at the Manchester venue.
But Parker landed significant shots, connecting with powerful clean blows in a match where the styles never quite clicked, with constant grabbing marring the fight.
The scoring judges had it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my best showing but what do champions do? They prevail," Buatsi stated in the arena as he was faced boos from the audience.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with Callum Smith in last winter - to secure a 20th pro success.
Several boxing experts believed the challenger, thirty-one, deserved the victory but the contender endured the second loss of his 28-fight professional journey.
Buatsi Earns Win in Dull Encounter
His career development has slowed in the past few years through contract problems and considerable time of lack of fights.
Once tipped as the rising talent of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what appears to be a last chance - under recent support.
He opened tentatively, with both competitors prepared to take risks in a calculated opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after suffering a hand injury mid-fight, was competing in only his second fight at light-heavyweight.
By the halfway stage, Parker had made it competitive, making life awkward for Buatsi, who worked behind a solid defense to edge the better periods.
The audience's tolerance diminished because of frequent holding, with Parker slipping to the canvas several times during grappling.
Parker ended stronger, but multiple periods were difficult to score. Nevertheless, former world champion the boxing analyst - working with the broadcast network - had it particularly wide for Parker, giving Buatsi just only one stanza.
Buatsi progresses, but with the presence of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the road to world glory - on this evidence - still looks steep.
Hatton Memorial Motivates Manchester Derby Fight
In the co-main event, Lyndon Arthur overcame Rea by divided decision in a outstanding all-Manchester battle to capture the European light-heavyweight title.
The stadium became quiet for a extremely emotional tribute before the fight as 10 bells tolled in honor of the city's native Ricky Hatton, who succumbed 46 years old in recently.
It was the first major televised match card in the city since Hatton's death. As the concluding sound faded, the quiet gave way to a shout of "there's only one Hatton".
The fighting within the ring equaled the emotion. Arthur was knocked down by a significant blow directly to the jaw in the early round, standing uncertainly to his position on the count of eight.
But the Manchester United-red equipment of Arthur soon advanced again. On the opposite side, Rea - in rival City blue - was marked up soon, significant bruising appearing under his orbital area as the fighters exchanged powerful shots.
The challenger, 27, landed power punches but the champion, 34, responded in kind with effective uppercuts as the action seldom decreased over the full distance.
Arthur narrowly won the decision with scoring tallies of even score, close margin and clearer margin, but both fighters were determined and full of heart, all the qualities their hero Hatton stood for.
