UK light-heavyweight Buatsi made a winning yet disappointing start to life under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a judges' verdict in a tight ten-round fight at the boxing arena.
But the challenger landed significant shots, landing some telling clean blows in a contest where the techniques didn't complement each other, with frequent clinching disrupting the action.
The scoring judges judged it 96-94 to the winner, with the third a 95-95.
"It wasn't my best showing but how do champions respond? They succeed," Buatsi stated in the ringside as he was greeted with disapproval from the spectators.
The British fighter bounced back after his initial pro loss - an epic battle with his previous opponent in last winter - to secure a twentieth professional win.
Various analysts felt Parker, 31, deserved the win but the Derbyshire fighter suffered the second loss of his 28-match professional journey.
Buatsi Earns Victory in Dull Encounter
The fighter's advancement has stalled in recent times through contract problems and extended periods of inactivity.
Once tipped as the rising talent of the British fight scene, he now stands trying to achieve expectations - maybe in what feels like a ultimate opportunity - under new promotional backing.
He started carefully, with neither fighter prepared to overcommit in a calculated opening few rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in 2022 after suffering a hand injury mid-fight, was competing in only his second fight at light heavyweight.
By the middle rounds, Parker had kept it close, causing problems for Buatsi, who utilized a protective stance to barely take the better stanzas.
The crowd's patience decreased because of frequent holding, with Parker slipping to the canvas various instances during grappling.
The underdog ended stronger, but many rounds were hard to judge. However, previous titleholder Carl Frampton - commentating on Dazn - had it particularly wide for the challenger, giving Buatsi just only one stanza.
Buatsi advances, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Tribute Inspires Manchester Derby Fight
In the secondary fight, Lyndon Arthur beat Bradley Rea by divided decision in a excellent Manchester vs Manchester fight to win the European light heavyweight belt.
The arena fell silent for a profoundly moving homage ahead of the contest as a bell ceremony sounded in memory of Manchester's own Hatton, who succumbed 46 years old in September.
It was the initial significant broadcast match card in the location since Hatton's passing. As the concluding sound disappeared, the stillness became a roar of "there's just one Ricky Hatton".
The fighting within the ring matched the emotion. Arthur was sent to the canvas by a powerful punch squarely on the face in the early round, standing uncertainly to his position on the eight count.
But the traditional red equipment of Arthur soon came forward again. Across the ring, Rea - in competitive blue - was injured soon, significant bruising forming under his face as the duo landed hard punches.
The challenger, 27, delivered effective strikes but Arthur, 34, matched the intensity with stinging uppercuts as the pace hardly diminished over 12 rounds.
The victor barely secured the result with official scores of 114-114, 115-113 and wider gap, but each competitor were relentless and full of heart, everything their hero Hatton stood for.
