UK light-heavyweight Buatsi secured a victory yet disappointing start to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a judges' verdict in a close 10-round bout at the boxing arena.
But Parker landed significant shots, delivering effective clean blows in a fight where the techniques failed to mesh, with excessive holding marring the contest.
The officials had it 96-94 in favor to Buatsi, with the final judge a 95-95 draw.
"It wasn't my greatest display but what defines champions? They win," the victor stated in the ring as he was greeted with boos from the crowd.
The British fighter returned to winning ways after his initial pro loss - an memorable fight with Callum Smith in last winter - to claim a twentieth professional win.
Some ringside observers thought the challenger, 31, merited the victory but the contender endured the second defeat of his 28-fight professional journey.
The Champion Earns Win in Slow Affair
His career development has stalled in the past few years through contract problems and extended periods of inactivity.
Previously predicted as the next star of UK boxing, he now finds himself trying to achieve expectations - possibly in what seems like a last chance - under new promotional backing.
He started carefully, with both competitors willing to be aggressive in a cagey opening few rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in 2022 after damaging his hand in the contest, was making just his second bout at light-heavyweight.
By the middle rounds, the underdog had made it competitive, causing problems for the favorite, who utilized a protective stance to edge the cleaner periods.
The audience's tolerance wore thin amid constant clinching, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog ended stronger, but several stanzas were hard to judge. Nevertheless, former world champion the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for Parker, scoring for Buatsi just one round.
Buatsi moves on, but with the presence of hard hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the path to championship success - on this evidence - still looks steep.
Hatton Memorial Inspires Manchester Derby Battle
In the supporting bout, Arthur overcame Bradley Rea by split-decision in a excellent Manchester vs Manchester contest to win the European light heavyweight title.
The arena fell silent for a deeply poignant memorial before the fight as 10 bells rang in remembrance of local hero Ricky Hatton, who succumbed 46 years old in last month.
It was the premier televised fight night in the location since the passing of Hatton. As the final chime disappeared, the quiet became a roar of "only one Ricky Hatton".
The fighting during the bout reflected the feeling. The eventual winner was floored by a powerful punch flush on the face in the early round, standing uncertainly to his position on the referee's count.
But the red-colored attire of the fighter soon pressed ahead again. Across the ring, the opponent - in opposing blue - was injured early, noticeable damage developing under his orbital area as the duo exchanged powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the intensity seldom decreased over twelve rounds.
Arthur barely secured the verdict with official scores of 114-114, close margin and clearer margin, but both fighters were determined and full of heart, all the qualities their idol Hatton represented.
