British light-heavyweight Buatsi made a winning yet unimpressive beginning to life under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a competitive 10-round bout at the Manchester venue.
But Parker found success, delivering effective individual punches in a contest where the techniques failed to mesh, with excessive holding disrupting the fight.
Two judges had it 96-94 to the winner, with the third a 95-95.
"It wasn't my greatest display but what do champions do? They prevail," the victor commented in the arena as he was greeted with boos from the spectators.
The Londoner got back to winning after his maiden career setback - an memorable fight with his previous opponent in last winter - to claim a 20th career victory.
Some ringside observers felt the challenger, 31, merited the decision but the Derbyshire fighter experienced the second setback of his 28-match professional journey.
The Champion Secures Win in Dull Affair
Buatsi's progress has plateaued in recent years through contract problems and extended periods of lack of fights.
Once tipped as the next star of UK boxing, he now finds himself trying to achieve expectations - perhaps in what feels like a final roll of the dice - under recent support.
He opened tentatively, with both competitors prepared to overcommit in a calculated opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was competing in only his second fight at light heavyweight.
By the middle rounds, the underdog had kept it close, causing problems for the favorite, who utilized a protective stance to edge the more effective rounds.
The crowd's patience diminished amid constant clinching, with Parker slipping to the canvas various instances during close exchanges.
The underdog ended stronger, but several stanzas were hard to judge. Nevertheless, former world champion the boxing analyst - commentating on Dazn - had it significantly in favor for the challenger, scoring for Buatsi just a single round.
Buatsi advances, but with the presence of power puncher Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the road to world glory - on this evidence - still seems difficult.
Hatton Memorial Inspires Manchester Derby Fight
In the secondary fight, Arthur beat Rea by split-decision in a excellent all-Manchester battle to win the continental championship.
The venue fell silent for a deeply poignant memorial ahead of the contest as a bell ceremony sounded in honor of Manchester's own Ricky Hatton, who passed away 46 years old in recently.
It was the premier televised match card in the city since Hatton's passing. As the final chime disappeared, the silence gave way to a roar of "there's only one Ricky Hatton".
The fighting inside the ropes reflected the feeling. The eventual winner was floored by a powerful punch squarely on the jaw in the initial stage, getting up unsteadily to his position on the referee's count.
But the red-colored equipment of Arthur soon advanced again. Across the ring, Rea - in rival City blue - was damaged soon, significant bruising appearing under his face as the duo landed hard punches.
Rea, twenty-seven, delivered effective strikes but the champion, 34, matched the intensity with effective uppercuts as the action hardly diminished over the full distance.
The victor edged the verdict with official scores of 114-114, narrow lead and clearer margin, but both fighters were relentless and courageous, everything their idol Hatton stood for.
