British light heavyweight Buatsi made a winning yet disappointing beginning to life under recent management with a points victory over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a judges' verdict in a close ten-round fight at the Co-op Live Arena.
But the challenger found success, delivering effective individual punches in a fight where the techniques never quite clicked, with frequent clinching spoiling the contest.
The scoring judges had it 96-94 in favor to the winner, with the third a even score.
"It wasn't my best showing but what defines champions? They succeed," the victor commented in the ringside as he was met by disapproval from the crowd.
The British fighter got back to winning after his first professional defeat - an memorable fight with Callum Smith in February - to claim a 20th career victory.
Various analysts believed Parker, 31, deserved the win but the Derbyshire fighter endured the second loss of his 28-fight professional journey.
The Champion Earns Victory in Dull Affair
His career development has slowed in recent years through promotional disputes and long spells of inactivity.
Previously predicted as the rising talent of the British fight scene, he now is positioned trying to achieve expectations - perhaps in what feels like a ultimate opportunity - under recent support.
He began cautiously, with both competitors willing to overcommit in a cagey initial rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after damaging his hand in the contest, was competing in only his second fight at light heavyweight.
By the middle rounds, the underdog had stayed in contention, making life awkward for Buatsi, who utilized a tight guard to edge the better rounds.
The audience's tolerance decreased because of constant clinching, with the challenger falling to the floor various instances during close exchanges.
The underdog ended stronger, but multiple periods were difficult to score. Although, ex-champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for Parker, giving Buatsi just a single round.
Buatsi moves on, but with the caliber of power puncher David Benavidez, and Russian champion Bivol leading the category, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Memorial Inspires Manchester Derby Contest
In the supporting bout, Arthur overcame Bradley Rea by close verdict in a outstanding local rivalry contest to secure the European light heavyweight championship.
The arena fell silent for a deeply poignant memorial before the fight as 10 bells tolled in honor of Manchester's own Ricky Hatton, who died aged 46 in recently.
It was the premier televised boxing event in the urban center since the passing of Hatton. As the concluding sound disappeared, the stillness transitioned to a roar of "only one Hatton".
The competition within the ring matched the sentiment. Arthur was floored by a left hook directly to the face in the early round, getting up unsteadily to his footing on the eight count.
But the traditional red equipment of Arthur soon came forward again. From the other corner, Rea - in competitive blue - was injured early, heavy swelling forming under his eye as the duo traded punishing blows.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, responded in kind with powerful upward punches as the pace rarely dropped over 12 rounds.
Arthur narrowly won the decision with scoring tallies of draw, close margin and 115-112, but both fighters were relentless and courageous, all the qualities their hero the legend embodied.
