UK light-heavyweight Buatsi made a winning 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 work rate appeared to earn him a split decision in a tight 10-round bout at the Co-op Live Arena.
But the challenger landed significant shots, connecting with powerful clean blows in a contest where the approaches didn't complement each other, with frequent clinching marring the contest.
Two judges scored it 96-94 for to the winner, with the remaining official a 95-95.
"It wasn't my best performance but how do champions respond? They win," Buatsi commented in the arena as he was greeted with negative reactions from the audience.
The British fighter bounced back after his maiden career setback - an epic battle with Callum Smith in last winter - to earn a 20th career victory.
Several boxing experts thought the challenger, 31, deserved the victory but the Derbyshire fighter experienced the second setback of his 28-bout professional journey.
Buatsi Secures Win in Uneventful Encounter
Buatsi's progress has plateaued in recent times through management issues and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now finds himself trying to realize his potential - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He began cautiously, with both competitors prepared to take risks in a tentative initial rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was participating in his second bout at light-heavyweight.
By the middle rounds, Parker had stayed in contention, creating difficulties for Buatsi, who worked behind a protective stance to edge the cleaner periods.
The audience's tolerance decreased because of constant clinching, with the challenger going down multiple occasions during grappling.
Parker closed well, but multiple periods were challenging to assess. Nevertheless, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just one round.
Buatsi advances, but with the presence of heavy hitter Benavidez, and Russian champion Bivol leading the category, the journey to titles - based on this performance - still appears challenging.
Hatton Homage Motivates Manchester Derby Fight
In the supporting bout, Arthur overcame Bradley Rea by split-decision in a outstanding local rivalry contest to capture the European light-heavyweight belt.
The venue became quiet for a extremely emotional tribute prior to the bout as 10 bells sounded in memory of Manchester's own Hatton, who succumbed 46 years old in September.
It was the premier televised fight night in the urban center since Hatton's passing. As the concluding sound disappeared, the quiet transitioned to a shout of "there's only one Hatton".
The competition within the ring reflected the feeling. Arthur was knocked down by a powerful punch directly to the jaw in the second round, standing uncertainly to his position on the count of eight.
But the red-colored equipment of the fighter soon pressed ahead again. From the other corner, Rea - in rival City blue - was damaged quickly, significant bruising developing under his eye as the fighters landed punishing blows.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the action rarely dropped over 12 rounds.
Arthur narrowly won the result with official scores of even score, close margin and clearer margin, but each competitor were relentless and brave, all the qualities their hero Hatton embodied.
