British light-heavyweight Buatsi made a winning yet unimpressive start 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 close 10-round contest at the boxing arena.
But the challenger landed significant shots, connecting with powerful single shots in a fight where the techniques failed to mesh, with frequent clinching spoiling the action.
The officials had it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my finest showing but what do champions do? They prevail," the victor commented in the arena as he was faced boos from the spectators.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Various analysts believed the challenger, 31, merited the win but the British boxer endured the second defeat of his 28-bout professional journey.
Buatsi Claims Triumph in Dull Match
His career development has plateaued in recent years through promotional disputes and considerable time of inactivity.
Previously predicted as the next star of British boxing, he now finds himself trying to fulfil that early promise - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He started carefully, with both competitors ready to overcommit in a tentative initial rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in two years ago after damaging his hand in the contest, was participating in his second appearance at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for the favorite, who worked behind a protective stance to barely take the cleaner rounds.
The crowd's patience wore thin amid frequent holding, with Parker falling to the floor multiple occasions during close exchanges.
The underdog ended stronger, but multiple periods were difficult to score. Although, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for the challenger, giving Buatsi just only one stanza.
Buatsi moves on, but with the presence of hard hitter Benavidez, and Russian champion Bivol leading the category, the road to world glory - on this evidence - still appears challenging.
Hatton Homage Motivates All-Manchester Contest
In the secondary fight, Arthur beat Rea by divided decision in a terrific local rivalry fight to secure the continental belt.
The venue fell silent for a deeply poignant homage ahead of the contest as 10 bells rang in memory of Manchester's own Ricky Hatton, who died at age 46 in September.
It was the premier televised boxing event in the city since Hatton's death. As the final chime faded, the stillness became a shout of "there's just one Hatton".
The competition inside the ropes reflected the emotion. Arthur was sent to the canvas by a left hook flush on the jaw in the early round, standing uncertainly to his footing on the eight count.
But the traditional red equipment of Arthur soon came forward again. On the opposite side, the opponent - in opposing blue - was injured quickly, heavy swelling appearing under his face as the fighters landed powerful shots.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with stinging uppercuts as the intensity hardly diminished over the full distance.
The victor barely secured the verdict with judges scorecards of even score, narrow lead and wider gap, but the two athletes were persistent and courageous, all the qualities their idol Hatton stood for.
