UK light-heavyweight Buatsi earned a win yet unimpressive beginning to life under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a judges' verdict in a tight ten-round bout at the boxing arena.
But Parker found success, landing some telling clean blows in a match where the techniques failed to mesh, with excessive holding spoiling the contest.
The scoring judges judged it 96-94 to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest display but what defines champions? They win," Buatsi said in the ring as he was greeted with disapproval from the spectators.
The Londoner got back to winning after his initial pro loss - an memorable fight with Callum Smith in February - to claim a 20th career victory.
Various analysts thought Parker, 31, should have been awarded the decision but the Derbyshire fighter endured the second defeat of his 28-fight professional journey.
Buatsi Earns Win in Slow Affair
The fighter's advancement has stalled in recent times through promotional disputes and extended periods of inactivity.
Earlier forecast as the future of UK boxing, he now stands trying to realize his potential - maybe in what seems like a final roll of the dice - under recent support.
He started carefully, with neither fighter prepared to be aggressive in a cagey early stages.
Parker, whose sole prior loss came at the lower weight class against his former opponent in two years ago after breaking his hand during the bout, was making just his second fight at the higher weight class.
By the middle rounds, Parker had made it competitive, making life awkward for the favorite, who worked behind a tight guard to edge the better stanzas.
The crowd's patience diminished because of regular grabbing, with Parker going down various instances during clinches.
Parker ended stronger, but several stanzas were hard to judge. Although, former world champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
Buatsi advances, but with the caliber of power puncher Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Tribute Motivates Local Rivalry Contest
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a terrific Manchester vs Manchester contest to capture the European light heavyweight championship.
The venue fell silent for a profoundly moving tribute before the fight as a bell ceremony rang in memory of local hero Hatton, who passed away aged 46 in September.
It was the premier televised fight night in the location since the passing of Hatton. As the last bell faded, the quiet became a shout of "there's just one Hatton".
The fighting inside the ropes matched the sentiment. Arthur was floored by a powerful punch flush on the chin in the second round, standing uncertainly to his position on the referee's count.
But the traditional red equipment of Arthur soon came forward again. On the opposite side, Rea - in rival City blue - was damaged quickly, significant bruising forming under his orbital area as the pair exchanged punishing blows.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, fought fire with fire with powerful upward punches as the action seldom decreased over 12 rounds.
The victor edged the verdict with official scores of even score, narrow lead and 115-112, but the two athletes were relentless and full of heart, all the qualities their idol the legend represented.
