British light-heavyweight Buatsi earned a win yet unimpressive start to life under new promoters with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a judges' verdict in a tight 10-round bout at the Co-op Live Arena.
But Parker found success, landing some telling individual punches in a match where the approaches never quite clicked, with frequent clinching disrupting the contest.
The officials judged it 96-94 to the winner, with the final judge a even score.
"It wasn't my finest display but how do champions respond? They prevail," the victor commented in the ringside as he was faced boos from the audience.
The Londoner got back to winning after his initial pro loss - an epic battle with his previous opponent in last winter - to secure a 20th career victory.
Some ringside observers felt Parker, 31, merited the win but the contender experienced the second defeat of his 28-match professional journey.
Buatsi Claims Triumph in Dull Encounter
The fighter's advancement has slowed in recent years through promotional disputes and considerable time of lack of fights.
Previously predicted as the rising talent of British boxing, he now finds himself trying to fulfil that early promise - perhaps in what appears to be a ultimate opportunity - under fresh management.
He opened tentatively, with both competitors ready to be aggressive in a calculated initial rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in two years ago after breaking his hand mid-fight, was making just his second appearance at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for the favorite, who utilized a protective stance to barely take the cleaner periods.
The crowd's patience wore thin amid frequent holding, with the challenger slipping to the canvas various instances during clinches.
Parker closed well, but multiple periods were hard to judge. Although, former world champion the boxing analyst - working with Dazn - had it strongly leaning for Parker, scoring for Buatsi just a single round.
The victor advances, but with the likes of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - on this evidence - still looks steep.
Hatton Memorial Motivates All-Manchester Battle
In the secondary fight, Lyndon Arthur overcame Bradley Rea by divided decision in a outstanding local rivalry contest to secure the continental championship.
The venue became quiet for a deeply poignant tribute prior to the bout as ten bells sounded in remembrance of local hero Hatton, who passed away 46 years old in last month.
It was the initial significant broadcast match card in the city since the passing of Hatton. As the last bell faded, the quiet gave way to a shout of "there's only one Ricky Hatton".
The competition within the ring reflected the emotion. Arthur was sent to the canvas by a powerful punch directly to the chin in the early round, standing uncertainly to his feet on the eight count.
But the traditional red equipment of the fighter soon came forward again. On the opposite side, Rea - in opposing blue - was injured soon, noticeable damage appearing under his orbital area as the pair traded punishing blows.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with effective uppercuts as the action rarely dropped over 12 rounds.
The victor edged the decision with judges scorecards of draw, 115-113 and clearer margin, but the two athletes were persistent and full of heart, all the qualities their hero the legend stood for.
