British light-heavyweight Buatsi made a winning yet unimpressive debut to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a judges' verdict in a close ten-round fight at the Co-op Live Arena.
But Parker landed significant shots, delivering effective single shots in a contest where the techniques didn't complement each other, with constant grabbing spoiling the fight.
Two judges scored it 96-94 to the winner, with the remaining official a even score.
"It wasn't my finest showing but what defines champions? They win," the victor said in the arena as he was met by boos from the audience.
The Londoner returned to winning ways after his initial pro loss - an memorable fight with Callum Smith in last winter - to secure a twentieth professional win.
Some ringside observers felt the challenger, 31, merited the victory but the contender experienced the second setback of his 28-fight career.
Buatsi Claims Victory in Slow Affair
Buatsi's progress has slowed in recent times through management issues and considerable time of lack of fights.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to realize his potential - maybe in what seems like a final roll of the dice - under new promotional backing.
He began cautiously, with both competitors prepared to be aggressive in a tentative early stages.
Parker, whose only previous defeat came at super middleweight against John Ryder in two years ago after breaking his hand mid-fight, was making just his second fight at light heavyweight.
By the fight's midpoint, the underdog had kept it close, creating difficulties for the favorite, who operated with a protective stance to narrowly win the better stanzas.
The audience's tolerance decreased amid constant clinching, with the challenger going down several times during grappling.
Parker ended stronger, but many rounds were challenging to assess. However, former world champion the boxing analyst - commentating on the broadcast network - had it strongly leaning for Parker, giving Buatsi just only one stanza.
The victor progresses, but with the presence of heavy hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still appears challenging.
Hatton Homage Inspires All-Manchester Battle
In the secondary fight, Arthur overcame Rea by split-decision in a terrific all-Manchester contest to capture the European light-heavyweight championship.
The arena became quiet for a profoundly moving tribute before the fight as 10 bells rang in honor of the city's native Hatton, who succumbed at age 46 in September.
It was the first major televised boxing event in the urban center since Hatton's death. As the final chime faded, the stillness gave way to a roar of "there's only one Ricky Hatton".
The action during the bout reflected the emotion. The eventual winner was knocked down by a significant blow squarely on the chin in the initial stage, rising shakily to his position on the referee's count.
But the traditional red equipment of Arthur soon advanced again. On the opposite side, the opponent - in competitive blue - was marked up soon, noticeable damage forming under his face as the pair traded hard punches.
Rea, 27, landed power punches but the champion, thirty-four, responded in kind with effective uppercuts as the pace hardly diminished over twelve rounds.
The victor narrowly won the result with scoring tallies of even score, narrow lead and clearer margin, but both fighters were persistent and brave, everything their inspiration the legend embodied.
