British light-heavyweight Buatsi earned a win yet underwhelming start to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a split decision in a close ten-round contest at the Manchester venue.
But Parker had his moments, delivering effective single shots in a match where the techniques never quite clicked, with excessive holding disrupting the fight.
The officials scored it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my best display but how do champions respond? They prevail," Buatsi said in the ring as he was met by negative reactions from the crowd.
The Londoner got back to winning after his first professional defeat - an thrilling contest with Callum Smith in last winter - to claim a twentieth professional win.
Various analysts believed Parker, thirty-one, should have been awarded the win but the Derbyshire fighter suffered the second setback of his 28-bout career.
The Champion Secures Victory in Dull Affair
His career development has slowed in recent times through contract problems and long spells of lack of fights.
Earlier forecast as the future of UK boxing, he now is positioned trying to fulfil that early promise - perhaps in what feels like a last chance - under fresh management.
He opened tentatively, with the two boxers ready to take risks in a calculated opening few rounds.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in two years ago after breaking his hand mid-fight, was making just his second appearance at light heavyweight.
By the fight's midpoint, the underdog had made it competitive, causing problems for Buatsi, who worked behind a protective stance to narrowly win the more effective stanzas.
The audience's tolerance wore thin because of constant clinching, with Parker slipping to the canvas various instances during grappling.
The underdog finished the stronger, but many rounds were difficult to score. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just a single round.
The victor progresses, but with the caliber of hard hitter Benavidez, and Russian champion Bivol leading the category, the journey to titles - on this evidence - still looks steep.
Hatton Tribute Fuels All-Manchester Fight
In the supporting bout, Lyndon Arthur defeated Bradley Rea by close verdict in a outstanding all-Manchester contest to win the European light-heavyweight title.
The arena became quiet for a extremely emotional homage prior to the bout as a bell ceremony tolled in honor of local hero Ricky Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast match card in the location since the passing of Hatton. As the last bell ended, the silence transitioned to a shout of "only one Hatton".
The fighting within the ring matched the emotion. Arthur was knocked down by a powerful punch squarely on the face in the initial stage, getting up unsteadily to his feet on the eight count.
But the red-colored equipment of the fighter soon pressed ahead again. Across the ring, Rea - in opposing blue - was marked up early, heavy swelling developing under his face as the pair traded powerful shots.
Rea, twenty-seven, delivered effective strikes but the champion, thirty-four, responded in kind with powerful upward punches as the intensity seldom decreased over the full distance.
The victor narrowly won the decision with judges scorecards of 114-114, 115-113 and clearer margin, but each competitor were persistent and brave, all the qualities their idol Hatton stood for.
