British light heavyweight Buatsi secured a victory yet disappointing debut to his career under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a tight 10-round fight at the Co-op Live Arena.
But the challenger had his moments, landing some telling individual punches in a contest where the styles didn't complement each other, with frequent clinching disrupting the action.
The scoring judges had it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my finest display but what defines champions? They win," Buatsi stated in the arena as he was greeted with disapproval from the audience.
The British fighter got back to winning after his initial pro loss - an thrilling contest with his previous opponent in February - to secure a 20th pro success.
Various analysts felt the challenger, thirty-one, deserved the decision but the British boxer endured the second loss of his 28-bout career.
Buatsi Claims Win in Slow Encounter
Buatsi's progress has stalled in the past few years through management issues and extended periods of lack of fights.
Earlier forecast as the rising talent of British boxing, he now stands trying to realize his potential - possibly in what seems like a ultimate opportunity - under fresh management.
He started carefully, with the two boxers willing to take risks in a cagey opening few rounds.
Parker, whose sole prior loss came at super-middleweight against his former opponent 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 made it competitive, creating difficulties for Buatsi, who utilized a protective stance to barely take the cleaner periods.
The crowd's patience wore thin amid regular grabbing, with Parker going down various instances during grappling.
The underdog finished the stronger, but many rounds were hard to judge. Although, ex-champion Carl Frampton - providing analysis for Dazn - had it particularly wide for Parker, scoring for Buatsi just a single round.
Buatsi moves on, but with the presence of power puncher David Benavidez, and Russian star Bivol ruling the division, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Battle
In the co-main event, Arthur beat Bradley Rea by split-decision in a outstanding local rivalry contest to win the European light heavyweight belt.
The stadium fell silent for a deeply poignant memorial ahead of the contest as ten bells sounded in remembrance of Manchester's own Ricky Hatton, who died at age 46 in September.
It was the first major televised fight night in the city since the passing of Hatton. As the final chime faded, the quiet gave way to a roar of "only one Ricky Hatton".
The action inside the ropes matched the feeling. Arthur was knocked down by a left hook directly to the jaw in the second round, standing uncertainly to his footing on the referee's count.
But the Manchester United-red equipment of Arthur soon came forward again. From the other corner, the opponent - in rival City blue - was marked up quickly, significant bruising forming under his orbital area as the pair landed hard punches.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, fought fire with fire with powerful upward punches as the intensity seldom decreased over the full distance.
Arthur barely secured the result with scoring tallies of draw, narrow lead and 115-112, but both fighters were persistent and full of heart, everything their inspiration Hatton represented.
