British light-heavyweight Buatsi made a winning yet disappointing start to his career under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a competitive ten-round fight at the Manchester venue.
But the challenger landed significant shots, delivering effective clean blows in a contest where the approaches failed to mesh, with excessive holding marring the contest.
Two judges had it 96-94 to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best display but what do champions do? They prevail," Buatsi said in the ring as he was greeted with disapproval from the audience.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with Callum Smith in last winter - to earn a 20th career victory.
Some ringside observers felt the challenger, 31, deserved the win but the Derbyshire fighter experienced the second defeat of his 28-match professional journey.
Buatsi Earns Triumph in Slow Affair
His career development has stalled in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - maybe in what seems like a last chance - under new promotional backing.
He started carefully, with both competitors ready to take risks in a cagey early stages.
Parker, whose only previous defeat came at super middleweight against his former opponent in 2022 after breaking his hand mid-fight, was participating in his second appearance at light-heavyweight.
By the middle rounds, the underdog had made it competitive, making life awkward for the favorite, who worked behind a solid defense to narrowly win the better stanzas.
The spectators' acceptance decreased during regular grabbing, with the challenger slipping to the canvas multiple occasions during clinches.
The underdog ended stronger, but several stanzas were challenging to assess. However, former world champion the boxing analyst - working with Dazn - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor moves on, but with the presence of heavy hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Homage Fuels Manchester Derby Battle
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a outstanding all-Manchester contest to secure the European light-heavyweight championship.
The arena became quiet for a deeply poignant memorial before the fight as a bell ceremony rang in memory of local hero Hatton, who died aged 46 in September.
It was the first major televised match card in the city since Hatton's passing. As the last bell ended, the quiet became a chant of "there's just one Hatton".
The fighting during the bout reflected the feeling. Arthur was floored by a significant blow squarely on the face in the early round, rising shakily to his footing on the referee's count.
But the Manchester United-red shorts of Arthur soon pressed ahead again. Across the ring, the opponent - in competitive blue - was damaged soon, significant bruising forming under his face as the pair exchanged hard punches.
The challenger, twenty-seven, delivered effective strikes but the champion, 34, responded in kind with effective uppercuts as the pace seldom decreased over twelve rounds.
The victor narrowly won the verdict with scoring tallies of even score, 115-113 and wider gap, but both fighters were persistent and brave, all the qualities their idol Hatton stood for.
