UK light heavyweight Buatsi earned a win yet underwhelming start to life under recent management with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a majority decision in a tight 10-round fight at the Co-op Live Arena.
But Parker found success, delivering effective individual punches in a contest where the techniques failed to mesh, with excessive holding disrupting the fight.
The officials judged it 96-94 for to the winner, with the third a even score.
"It wasn't my best performance but what do champions do? They prevail," the victor commented in the ring as he was met by boos from the crowd.
The Londoner returned to winning ways after his maiden career setback - an thrilling contest with Callum Smith in February - to earn a twentieth professional win.
Various analysts believed the challenger, 31, should have been awarded the victory but the British boxer endured the second setback of his 28-fight professional journey.
Buatsi Secures Triumph in Uneventful Match
His career development has plateaued in recent times through promotional disputes and considerable time of inactivity.
Earlier forecast as the rising talent of UK boxing, he now finds himself trying to fulfil that early promise - possibly in what appears to be a ultimate opportunity - under recent support.
He began cautiously, with neither fighter ready to overcommit in a cagey initial rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in two years ago after breaking his hand mid-fight, was competing in only his second appearance at light-heavyweight.
By the fight's midpoint, Parker had made it competitive, creating difficulties for the favorite, who operated with a solid defense to barely take the more effective rounds.
The audience's tolerance wore thin during constant clinching, with Parker falling to the floor multiple occasions during close exchanges.
Parker ended stronger, but multiple periods were challenging to assess. Nevertheless, previous titleholder Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, scoring for Buatsi just one round.
Buatsi moves on, but with the likes of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - judging by this showing - still appears challenging.
Ricky Hatton Homage Inspires Manchester Derby Battle
In the supporting bout, Arthur overcame Bradley Rea by divided decision in a outstanding Manchester vs Manchester contest to capture the continental belt.
The venue grew hushed for a extremely emotional tribute prior to the bout as a bell ceremony tolled in honor of the city's native Hatton, who died 46 years old in recently.
It was the premier televised match card in the urban center since the passing of Hatton. As the final chime ended, the quiet gave way to a chant of "there's only one Hatton".
The fighting during the bout reflected the emotion. The eventual winner was sent to the canvas by a left hook directly to the face in the initial stage, rising shakily to his footing on the referee's count.
But the traditional red shorts of the fighter soon came forward again. From the other corner, the opponent - in opposing blue - was injured early, noticeable damage forming under his eye as the pair exchanged punishing blows.
The challenger, 27, connected with strong blows but the champion, thirty-four, matched the intensity with stinging uppercuts as the action rarely dropped over twelve rounds.
The victor narrowly won the decision with judges scorecards of 114-114, close margin and clearer margin, but the two athletes were relentless and courageous, everything their inspiration the legend embodied.
