UK light-heavyweight Buatsi secured a victory yet disappointing debut to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level appeared to earn him a judges' verdict in a tight 10-round fight at the Co-op Live Arena.
But Parker found success, delivering effective clean blows in a contest where the approaches never quite clicked, with excessive holding marring the action.
The scoring judges scored it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my greatest showing but how do champions respond? They succeed," the victor stated in the ring as he was greeted with negative reactions from the spectators.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with Callum Smith in last winter - to earn a twentieth professional win.
Various analysts felt the challenger, thirty-one, deserved the victory but the Derbyshire fighter endured the second defeat of his 28-match professional journey.
The Champion Secures Victory in Slow Match
The fighter's advancement has slowed in recent times through management issues and considerable time of inactivity.
Once tipped as the rising talent of UK boxing, he now is positioned trying to achieve expectations - possibly in what feels like a last chance - under fresh management.
He started carefully, with both competitors ready to take risks in a tentative opening few rounds.
The challenger, whose only previous defeat came at super middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was competing in only his second appearance at the higher weight class.
By the middle rounds, the underdog had kept it close, creating difficulties for the favorite, who operated with a solid defense to narrowly win the more effective periods.
The crowd's patience diminished amid frequent holding, with Parker going down multiple occasions during grappling.
The underdog ended stronger, but several stanzas were hard to judge. Although, previous titleholder the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, giving Buatsi just one round.
Buatsi progresses, but with the presence of power puncher Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - based on this performance - still seems difficult.
Ricky Hatton Homage Motivates Manchester Derby Contest
In the secondary fight, Arthur defeated Bradley Rea by split-decision in a outstanding local rivalry fight to win the European light-heavyweight championship.
The venue fell silent for a deeply poignant homage before the fight as 10 bells sounded in memory of Manchester's own Ricky Hatton, who succumbed aged 46 in September.
It was the premier televised boxing event in the urban center since the passing of Hatton. As the last bell ended, the quiet transitioned to a chant of "only one Ricky Hatton".
The action during the bout equaled the sentiment. Arthur was sent to the canvas by a significant blow directly to the face in the initial stage, rising shakily to his footing on the eight count.
But the traditional red equipment of the fighter soon came forward again. On the opposite side, the opponent - in competitive blue - was marked up quickly, heavy swelling developing under his eye as the duo traded punishing blows.
The challenger, 27, delivered effective strikes but the champion, 34, fought fire with fire with stinging uppercuts as the intensity rarely dropped over 12 rounds.
Arthur barely secured the verdict with official scores of even score, narrow lead and clearer margin, but each competitor were relentless and courageous, exactly what their inspiration Hatton stood for.
