UK light-heavyweight Buatsi earned a win yet underwhelming beginning to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a competitive 10-round fight at the boxing arena.
But Parker landed significant shots, connecting with powerful clean blows in a match where the styles failed to mesh, with excessive holding spoiling the contest.
The officials judged it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my greatest display but what defines champions? They prevail," the victor said in the arena as he was faced disapproval from the crowd.
The Londoner bounced back after his initial pro loss - an epic battle with Callum Smith in February - to earn a 20th pro success.
Some ringside observers felt the challenger, thirty-one, merited the decision but the British boxer experienced the second loss of his 28-match professional journey.
The Champion Claims Win in Dull Affair
Buatsi's progress has stalled in the past few years through contract problems and extended periods of lack of fights.
Once tipped as the next star of the British fight scene, he now finds himself trying to achieve expectations - possibly in what feels like a ultimate opportunity - under recent support.
He began cautiously, with neither fighter willing to be aggressive in a cagey opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after suffering a hand injury mid-fight, was competing in only his second bout at the higher weight class.
By the middle rounds, the underdog had stayed in contention, causing problems for Buatsi, who utilized a protective stance to edge the better periods.
The audience's tolerance decreased because of constant clinching, with the challenger slipping to the canvas various instances during clinches.
The underdog finished the stronger, but many rounds were challenging to assess. Although, ex-champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for Parker, giving Buatsi just only one stanza.
Buatsi advances, but with the likes of power puncher David Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Memorial Inspires Local Rivalry Battle
In the supporting bout, Arthur overcame Rea by close verdict in a outstanding local rivalry fight to win the European light-heavyweight championship.
The venue grew hushed for a extremely emotional tribute before the fight as 10 bells rang in memory of the city's native Hatton, who died at age 46 in September.
It was the initial significant broadcast fight night in the city since Hatton's passing. As the concluding sound ended, the silence gave way to a chant of "there's only one Hatton".
The fighting inside the ropes matched the sentiment. Arthur was sent to the canvas by a significant blow directly to the face in the early round, standing uncertainly to his feet on the referee's count.
But the red-colored attire of Arthur soon came forward again. Across the ring, Rea - in competitive blue - was marked up soon, significant bruising developing under his face as the pair landed hard punches.
Rea, 27, delivered effective strikes but the champion, 34, matched the intensity with powerful upward punches as the action hardly diminished over 12 rounds.
The victor narrowly won the result with judges scorecards of draw, close margin and 115-112, but each competitor were determined and full of heart, exactly what their hero the legend embodied.
