British light-heavyweight Buatsi earned a win yet unimpressive beginning to life under recent management with a decision win over Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a majority decision in a tight 10-round bout at the Manchester venue.
But the challenger found success, delivering effective clean blows in a match where the techniques failed to mesh, with frequent clinching disrupting the fight.
The officials scored it 96-94 for to Buatsi, with the third a 95-95 draw.
"It wasn't my best showing but what do champions do? They win," Buatsi commented in the arena as he was faced negative reactions from the crowd.
The British fighter bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to claim a twentieth professional win.
Some ringside observers believed the challenger, thirty-one, merited the decision but the contender endured the second setback of his 28-bout career.
Buatsi Claims Victory in Uneventful Affair
The fighter's advancement has slowed in recent times through contract problems and considerable time of lack of fights.
Earlier forecast as the future of the British fight scene, he now finds himself trying to achieve expectations - perhaps in what seems like a ultimate opportunity - under recent support.
He started carefully, with the two boxers ready to take risks in a calculated opening few rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent in two years ago after damaging his hand mid-fight, was participating in his second bout at light heavyweight.
By the fight's midpoint, the underdog had kept it close, making life awkward for the favorite, who worked behind a protective stance to barely take the more effective periods.
The spectators' acceptance decreased because of constant clinching, with Parker slipping to the canvas various instances during grappling.
The underdog ended stronger, but several stanzas were challenging to assess. Although, previous titleholder Carl Frampton - working with Dazn - had it strongly leaning for the challenger, giving Buatsi just one round.
The victor moves on, but with the presence of heavy hitter Benavidez, and Russian champion Bivol dominating the weight class, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Homage Fuels All-Manchester Battle
In the secondary fight, Arthur defeated Rea by split-decision in a terrific Manchester vs Manchester battle to secure the European light-heavyweight belt.
The stadium grew hushed for a deeply poignant memorial ahead of the contest as a bell ceremony tolled in remembrance of the city's native Ricky Hatton, who passed away 46 years old in recently.
It was the first major televised fight night in the urban center since the passing of Hatton. As the last bell disappeared, the quiet transitioned to a shout of "there's just one Ricky Hatton".
The competition inside the ropes matched the emotion. Arthur was knocked down by a significant blow flush on the face in the second round, getting up unsteadily to his position on the eight count.
But the red-colored shorts of the fighter soon pressed ahead again. From the other corner, the opponent - in rival City blue - was marked up soon, significant bruising appearing under his eye as the pair exchanged powerful shots.
The challenger, twenty-seven, delivered effective strikes but the champion, thirty-four, matched the intensity with stinging uppercuts as the intensity seldom decreased over 12 rounds.
Arthur edged the result with official scores of draw, 115-113 and wider gap, but each competitor were relentless and brave, exactly what their hero the legend stood for.
