British light-heavyweight Buatsi made a winning yet disappointing beginning 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 split decision in a tight 10-round fight at the Manchester venue.
But Parker landed significant shots, landing some telling clean blows in a fight where the styles never quite clicked, with constant grabbing spoiling the fight.
The scoring judges judged it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my greatest performance but what do champions do? They succeed," the victor said in the arena as he was met by boos from the crowd.
The Londoner got back to winning after his first professional defeat - an epic battle with Callum Smith in February - to secure a twentieth professional win.
Several boxing experts thought the challenger, thirty-one, merited the victory but the British boxer experienced the second defeat of his 28-bout career.
Buatsi Claims Triumph in Slow Match
Buatsi's progress has plateaued in the past few years through management issues and extended periods of lack of fights.
Previously predicted as the future of British boxing, he now is positioned trying to achieve expectations - perhaps in what feels like a final roll of the dice - under fresh management.
He opened tentatively, with neither fighter prepared to be aggressive in a calculated initial rounds.
Parker, whose sole prior loss came at the lower weight class against his former opponent in two years ago after suffering a hand injury during the bout, was making just his second bout at light heavyweight.
By the halfway stage, Parker had stayed in contention, making life awkward for Buatsi, who utilized a protective stance to edge the better periods.
The audience's tolerance diminished during regular grabbing, with Parker falling to the floor several times during clinches.
The underdog ended stronger, but several stanzas were challenging to assess. Although, former world champion Carl Frampton - commentating on the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just one round.
Buatsi progresses, but with the likes of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - based on this performance - still looks steep.
Hatton Tribute Fuels Manchester Derby Contest
In the co-main event, Arthur beat Rea by split-decision in a outstanding Manchester vs Manchester fight to secure the European light-heavyweight title.
The stadium became quiet for a profoundly moving tribute ahead of the contest as a bell ceremony sounded in memory of local hero Hatton, who died aged 46 in September.
It was the initial significant broadcast boxing event in the location since Hatton's passing. As the last bell ended, the quiet became a shout of "there's just one Hatton".
The action within the ring equaled the sentiment. Arthur was sent to the canvas by a significant blow directly to the jaw in the early round, rising shakily to his feet on the eight count.
But the Manchester United-red attire of Arthur soon advanced again. On the opposite side, the opponent - in competitive blue - was injured soon, noticeable damage forming under his face as the duo traded powerful shots.
The challenger, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the pace rarely dropped over the full distance.
Arthur barely secured the decision with judges scorecards of even score, close margin and wider gap, but the two athletes were determined and brave, all the qualities their hero the legend represented.
