British light-heavyweight Buatsi earned a win yet disappointing debut to his career under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a majority decision in a tight ten-round fight at the Manchester venue.
But the challenger landed significant shots, connecting with powerful clean blows in a match where the techniques never quite clicked, with constant grabbing spoiling the action.
The scoring judges judged it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my finest display but what do champions do? They prevail," the victor commented in the ringside as he was greeted with negative reactions from the crowd.
The Londoner got back to winning after his initial pro loss - an epic battle with his previous opponent in February - to secure a 20th pro success.
Several boxing experts thought the challenger, thirty-one, merited the win but the contender suffered the second defeat of his 28-fight professional journey.
The Champion Secures Win in Dull Encounter
His career development has plateaued in the past few years through promotional disputes and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now finds himself trying to achieve expectations - possibly in what appears to be a final roll of the dice - under new promotional backing.
He opened tentatively, with the two boxers ready to overcommit in a cagey initial rounds.
The challenger, whose sole prior loss came at super-middleweight against John Ryder in two years ago after breaking his hand mid-fight, was competing in only his second fight at the higher weight class.
By the fight's midpoint, Parker had stayed in contention, creating difficulties for the favorite, who operated with a tight guard to barely take the more effective rounds.
The audience's tolerance diminished during constant clinching, with the challenger slipping to the canvas several times during grappling.
Parker finished the stronger, but several stanzas were challenging to assess. Nevertheless, previous titleholder Carl Frampton - commentating on the broadcast network - had it strongly leaning for Parker, awarding Buatsi just only one stanza.
Buatsi progresses, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the road to world glory - judging by this showing - still appears challenging.
Ricky Hatton Homage Inspires Manchester Derby Fight
In the secondary fight, Lyndon Arthur defeated Rea by close verdict in a excellent all-Manchester fight to capture the European light-heavyweight championship.
The arena became quiet for a profoundly moving homage prior to the bout as a bell ceremony sounded in remembrance of Manchester's own Hatton, who passed away aged 46 in September.
It was the initial significant broadcast fight night in the city since Hatton's death. As the final chime faded, the silence became a roar of "there's just one Hatton".
The fighting inside the ropes matched the sentiment. Arthur was sent to the canvas by a significant blow directly to the chin in the early round, rising shakily to his feet on the count of eight.
But the red-colored equipment of the fighter soon came forward again. Across the ring, Rea - in competitive blue - was marked up quickly, heavy swelling developing under his face as the fighters landed punishing blows.
The challenger, twenty-seven, landed power punches but the champion, 34, fought fire with fire with effective uppercuts as the pace seldom decreased over the full distance.
The victor narrowly won the decision with judges scorecards of draw, close margin and wider gap, but both fighters were persistent and courageous, all the qualities their hero the legend stood for.
