UK light-heavyweight Buatsi earned a win yet underwhelming debut to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a majority decision in a close 10-round bout at the boxing arena.
But Parker had his moments, delivering effective individual punches in a contest where the approaches didn't complement each other, with frequent clinching marring the fight.
The officials judged it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest display but what do champions do? They prevail," the victor said in the ring as he was met by negative reactions from the audience.
The British fighter got back to winning after his first professional defeat - an thrilling contest with Callum Smith in February - to secure a 20th career victory.
Several boxing experts believed the challenger, thirty-one, deserved the victory but the contender endured the second defeat of his 28-fight career.
Buatsi Earns Victory in Slow Affair
Buatsi's progress has slowed in recent times through management issues and extended periods of lack of fights.
Previously predicted as the rising talent of British boxing, he now is positioned trying to realize his potential - possibly in what appears to be a final roll of the dice - under recent support.
He began cautiously, with the two boxers ready to be aggressive in a cagey early stages.
Parker, whose only previous defeat came at super middleweight against John Ryder in 2022 after breaking his hand during the bout, was making just his second appearance at light-heavyweight.
By the halfway stage, Parker had made it competitive, creating difficulties for Buatsi, who utilized a tight guard to barely take the better periods.
The spectators' acceptance wore thin amid regular grabbing, with Parker going down several times during grappling.
The underdog ended stronger, but many rounds were difficult to score. Although, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, giving Buatsi just one round.
Buatsi progresses, but with the presence of power puncher Benavidez, and Russian star Bivol dominating the weight class, the path to championship success - on this evidence - still seems difficult.
Ricky Hatton Memorial Motivates All-Manchester Battle
In the secondary fight, Lyndon Arthur defeated Rea by close verdict in a outstanding all-Manchester fight to capture the continental belt.
The venue fell silent for a extremely emotional homage ahead of the contest as a bell ceremony tolled in memory of local hero Ricky Hatton, who died 46 years old in recently.
It was the initial significant broadcast fight night in the city since Hatton's death. As the final chime faded, the silence became a shout of "there's only one Ricky Hatton".
The fighting within the ring matched the feeling. Arthur was knocked down by a significant blow directly to the jaw in the second round, standing uncertainly to his feet on the referee's count.
But the red-colored attire of the fighter soon pressed ahead again. From the other corner, the opponent - in opposing blue - was marked up soon, significant bruising appearing under his face as the pair landed punishing blows.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, fought fire with fire with effective uppercuts as the pace seldom decreased over the full distance.
The victor edged the verdict with official scores of even score, 115-113 and 115-112, but both fighters were persistent and courageous, all the qualities their idol Hatton stood for.
