UK light heavyweight Buatsi earned a win yet underwhelming beginning to life under recent management with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a close 10-round bout at the boxing arena.
But Parker landed significant shots, delivering effective individual punches in a fight where the techniques failed to mesh, with excessive holding spoiling the contest.
Two judges judged it 96-94 to the winner, with the third a even score.
"It wasn't my best showing but what do champions do? They succeed," the victor stated in the arena as he was faced negative reactions from the spectators.
The Londoner bounced back after his first professional defeat - an epic battle with Callum Smith in February - to claim a twentieth professional win.
Several boxing experts felt Parker, 31, deserved the win but the contender suffered the second loss of his 28-fight professional journey.
Buatsi Secures Win in Uneventful Encounter
His career development has slowed in the past few years through promotional disputes and extended periods of inactivity.
Earlier forecast as the rising talent of British boxing, he now finds himself trying to achieve expectations - perhaps in what seems like a ultimate opportunity - under new promotional backing.
He started carefully, with the two boxers prepared to be aggressive in a tentative initial rounds.
Parker, whose single earlier setback came at the lower weight class against his former opponent in 2022 after breaking his hand mid-fight, was participating in his second fight at the higher weight class.
By the halfway stage, the underdog had kept it close, creating difficulties for Buatsi, who operated with a solid defense to edge the better periods.
The spectators' acceptance diminished amid frequent holding, with Parker going down several times during close exchanges.
Parker closed well, but several stanzas were hard to judge. Nevertheless, ex-champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just a single round.
Buatsi advances, but with the presence of power puncher Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Memorial Fuels Local Rivalry Contest
In the secondary fight, Arthur defeated Bradley Rea by divided decision in a outstanding Manchester vs Manchester fight to secure the continental belt.
The stadium became quiet for a extremely emotional memorial prior to the bout as 10 bells sounded in honor of the city's native Hatton, who passed away at age 46 in last month.
It was the premier televised fight night in the urban center since Hatton's passing. As the last bell ended, the silence transitioned to a chant of "only one Hatton".
The action inside the ropes reflected the sentiment. The eventual winner was floored by a significant blow flush on the face in the second round, rising shakily to his position on the count of eight.
But the Manchester United-red shorts of the fighter soon pressed ahead again. On the opposite side, Rea - in opposing blue - was damaged quickly, noticeable damage developing under his orbital area as the pair exchanged hard punches.
Rea, twenty-seven, landed power punches but the champion, 34, fought fire with fire with powerful upward punches as the intensity rarely dropped over the full distance.
Arthur barely secured the result with scoring tallies of draw, 115-113 and wider gap, but each competitor were persistent and brave, everything their hero Hatton represented.
