British light-heavyweight Buatsi made a winning yet disappointing beginning to his career under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a judges' verdict in a competitive 10-round fight at the Manchester venue.
But the challenger found success, connecting with powerful single shots in a match where the styles never quite clicked, with excessive holding disrupting the fight.
The scoring judges judged it 96-94 to the winner, with the remaining official a 95-95.
"It wasn't my finest display but what defines champions? They win," Buatsi commented in the arena as he was met by disapproval from the audience.
The Londoner got back to winning after his maiden career setback - an memorable fight with Callum Smith in last winter - to secure a 20th career victory.
Some ringside observers felt Parker, 31, should have been awarded the win but the Derbyshire fighter experienced the second setback of his 28-fight professional journey.
The Champion Secures Triumph in Slow Affair
His career development has plateaued in recent times through contract problems and long spells of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now finds himself trying to realize his potential - perhaps in what appears to be a ultimate opportunity - under fresh management.
He opened tentatively, with neither fighter ready to be aggressive in a cagey initial rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in two years ago after damaging his hand in the contest, was participating in his second bout at light-heavyweight.
By the fight's midpoint, Parker had kept it close, making life awkward for Buatsi, who operated with a protective stance to edge the more effective stanzas.
The spectators' acceptance diminished amid frequent holding, with Parker falling to the floor various instances during close exchanges.
Parker finished the stronger, but several stanzas were hard to judge. Nevertheless, former world champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, giving Buatsi just a single round.
The victor advances, but with the caliber of heavy hitter Benavidez, and Russian star Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Tribute Motivates All-Manchester Battle
In the supporting bout, Lyndon Arthur overcame Bradley Rea by split-decision in a excellent Manchester vs Manchester battle to secure the European light-heavyweight title.
The stadium became quiet for a extremely emotional memorial ahead of the contest as ten bells tolled in memory of local hero Ricky Hatton, who died at age 46 in September.
It was the premier televised fight night in the city since Hatton's death. As the concluding sound faded, the silence transitioned to a roar of "there's only one Hatton".
The competition during the bout matched the emotion. Arthur was knocked down by a powerful punch directly to the chin in the second round, standing uncertainly to his feet on the eight count.
But the Manchester United-red attire of the fighter soon came forward again. From the other corner, Rea - in opposing blue - was marked up quickly, significant bruising developing under his eye as the duo exchanged powerful shots.
Rea, 27, landed power punches but Arthur, 34, responded in kind with stinging uppercuts as the intensity seldom decreased over the full distance.
Arthur narrowly won the result with official scores of even score, close margin and clearer margin, but both fighters were determined and full of heart, exactly what their hero the legend embodied.
