British light-heavyweight Buatsi made a winning yet disappointing start to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output likely gained him a split decision in a tight 10-round contest at the Manchester venue.
But Parker found success, connecting with powerful clean blows in a contest where the approaches never quite clicked, with excessive holding disrupting the fight.
The officials scored it 96-94 for to Buatsi, with the final judge a 95-95 draw.
"It wasn't my greatest display but what do champions do? They succeed," Buatsi commented in the ring as he was faced negative reactions from the spectators.
The British fighter got back to winning after his maiden career setback - an thrilling contest with Callum Smith in last winter - to earn a 20th pro success.
Some ringside observers thought the challenger, thirty-one, should have been awarded the decision but the Derbyshire fighter suffered the second loss of his 28-match career.
The Champion Claims Win in Dull Match
His career development has plateaued in recent years through contract problems and extended periods of lack of fights.
Once tipped as the rising talent of British boxing, he now is positioned trying to realize his potential - maybe in what feels like a final roll of the dice - under recent support.
He started carefully, with both competitors ready to overcommit in a cagey opening few rounds.
The challenger, whose only previous defeat came at super-middleweight against his former opponent in 2022 after suffering a hand injury mid-fight, was making just his second bout at light heavyweight.
By the halfway stage, Parker had stayed in contention, creating difficulties for Buatsi, who utilized a solid defense to barely take the better rounds.
The crowd's patience wore thin because of frequent holding, with Parker falling to the floor various instances during clinches.
The underdog ended stronger, but several stanzas were difficult to score. However, former world champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just one round.
The victor moves on, but with the likes of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Memorial Motivates Manchester Derby Battle
In the supporting bout, Arthur overcame Rea by close verdict in a outstanding all-Manchester contest to capture the European light-heavyweight title.
The venue grew hushed for a profoundly moving homage ahead of the contest as ten bells sounded in memory of the city's native Ricky Hatton, who succumbed 46 years old in recently.
It was the premier televised match card in the urban center since Hatton's passing. As the final chime faded, the stillness became a shout of "there's just one Ricky Hatton".
The competition within the ring matched the emotion. The eventual winner was floored by a left hook directly to the face in the second round, getting up unsteadily to his feet on the count of eight.
But the red-colored equipment of Arthur soon came forward again. On the opposite side, Rea - in opposing blue - was injured soon, noticeable damage forming under his orbital area as the pair exchanged powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, thirty-four, fought fire with fire with effective uppercuts as the intensity rarely dropped over the full distance.
The victor edged the result with official scores of 114-114, narrow lead and wider gap, but both fighters were relentless and courageous, all the qualities their inspiration the legend represented.
