UK light-heavyweight Buatsi earned a win yet disappointing beginning to life under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a majority decision in a close ten-round fight at the Manchester venue.
But the challenger had his moments, delivering effective single shots in a contest where the approaches never quite clicked, with constant grabbing marring the contest.
Two judges had it 96-94 in favor to Buatsi, with the remaining official a 95-95.
"It wasn't my finest performance but what do champions do? They succeed," the victor stated in the ring as he was greeted with boos from the audience.
The British fighter bounced back after his first professional defeat - an epic battle with Callum Smith in February - to earn a twentieth professional win.
Some ringside observers believed Parker, thirty-one, merited the win but the British boxer suffered the second defeat of his 28-bout career.
The Champion Claims Win in Slow Affair
Buatsi's progress has slowed in the past few years through promotional disputes and long spells of inactivity.
Previously predicted as the future of British boxing, he now is positioned trying to fulfil that early promise - perhaps in what feels like a final roll of the dice - under fresh management.
He opened tentatively, with the two boxers prepared to overcommit in a calculated early stages.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand in the contest, was competing in only his second fight at the higher weight class.
By the fight's midpoint, Parker had stayed in contention, causing problems for Buatsi, who operated with a protective stance to narrowly win the more effective rounds.
The audience's tolerance diminished amid frequent holding, with Parker slipping to the canvas several times during clinches.
The underdog closed well, but multiple periods were challenging to assess. Although, ex-champion Carl Frampton - commentating on Dazn - had it particularly wide for the challenger, awarding Buatsi just a single round.
The victor advances, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - on this evidence - still appears challenging.
Hatton Homage Fuels Local Rivalry Battle
In the supporting bout, Lyndon Arthur overcame Rea by close verdict in a outstanding all-Manchester contest to capture the continental belt.
The stadium grew hushed for a extremely emotional homage prior to the bout as a bell ceremony tolled in honor of the city's native Ricky Hatton, who passed away at age 46 in recently.
It was the premier televised match card in the location since Hatton's passing. As the concluding sound faded, the stillness became a roar of "there's only one Ricky Hatton".
The competition during the bout matched the sentiment. Arthur was sent to the canvas by a significant blow flush on the face in the initial stage, standing uncertainly to his position on the referee's count.
But the traditional red shorts of Arthur soon came forward again. From the other corner, the opponent - in opposing blue - was injured early, heavy swelling developing under his orbital area as the fighters exchanged hard punches.
Rea, twenty-seven, connected with strong blows but the champion, thirty-four, fought fire with fire with powerful upward punches as the action hardly diminished over twelve rounds.
The victor barely secured the verdict with scoring tallies of 114-114, close margin and clearer margin, but the two athletes were persistent and brave, all the qualities their inspiration Hatton embodied.
