British light-heavyweight Buatsi earned a win yet disappointing debut to his career under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a split decision in a close ten-round contest at the Co-op Live Arena.
But Parker had his moments, landing some telling individual punches in a match where the styles didn't complement each other, with constant grabbing marring the action.
Two judges judged it 96-94 in favor to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best display but what defines champions? They prevail," Buatsi stated in the arena as he was faced boos from the audience.
The Londoner returned to winning ways after his initial pro loss - an thrilling contest with his previous opponent in February - to secure a twentieth professional win.
Several boxing experts thought the challenger, 31, should have been awarded the win but the Derbyshire fighter endured the second defeat of his 28-fight professional journey.
Buatsi Claims Win in Uneventful Match
The fighter's advancement has stalled in recent years through management issues and extended periods of inactivity.
Previously predicted as the future of British boxing, he now finds himself trying to realize his potential - possibly in what feels like a last chance - under fresh management.
He started carefully, with neither fighter prepared to overcommit in a cagey early stages.
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 the higher weight class.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who worked behind a solid defense to edge the better rounds.
The crowd's patience wore thin amid frequent holding, with Parker slipping to the canvas multiple occasions during grappling.
Parker closed well, but many rounds were challenging to assess. Nevertheless, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just a single round.
The victor moves on, but with the presence of hard hitter Benavidez, and Russian star Bivol ruling the division, the journey to titles - judging by this showing - still looks steep.
Hatton Homage Motivates Manchester Derby Contest
In the supporting bout, Lyndon Arthur overcame Rea by split-decision in a outstanding all-Manchester contest to secure the continental championship.
The stadium fell silent for a deeply poignant homage prior to the bout as 10 bells sounded in memory of Manchester's own Ricky Hatton, who died aged 46 in September.
It was the first major televised fight night in the urban center since Hatton's death. As the last bell ended, the stillness gave way to a chant of "there's only one Hatton".
The action within the ring reflected the sentiment. The eventual winner was sent to the canvas by a powerful punch squarely on the face in the second round, rising shakily to his footing on the eight count.
But the red-colored attire of the fighter soon pressed ahead again. From the other corner, the opponent - in rival City blue - was injured early, significant bruising developing under his face as the pair traded hard punches.
The challenger, twenty-seven, landed power punches but Arthur, 34, matched the intensity with powerful upward punches as the intensity hardly diminished over the full distance.
Arthur edged the decision with scoring tallies of 114-114, narrow lead and wider gap, but the two athletes were relentless and brave, everything their hero Hatton embodied.
