UK light-heavyweight Buatsi made a winning yet unimpressive debut to life under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a majority decision in a close ten-round bout at the Manchester venue.
But Parker found success, connecting with powerful clean blows in a fight where the approaches never quite clicked, with constant grabbing marring the action.
The scoring judges judged it 96-94 to the winner, with the remaining official a 95-95 draw.
"It wasn't my finest display but what do champions do? They win," Buatsi said in the arena as he was greeted with negative reactions from the crowd.
The Londoner got back to winning after his maiden career setback - an memorable fight with Callum Smith in February - to secure a 20th career victory.
Several boxing experts believed the challenger, thirty-one, merited the victory but the Derbyshire fighter suffered the second defeat of his 28-bout professional journey.
The Champion Claims Victory in Dull Match
The fighter's advancement has slowed in recent times through contract problems and long spells of inactivity.
Earlier forecast as the rising talent of British boxing, he now finds himself trying to achieve expectations - perhaps in what feels like a final roll of the dice - under fresh management.
He opened tentatively, with the two boxers ready to be aggressive in a tentative early stages.
Parker, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand in the contest, was participating in his second appearance at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, creating difficulties for the favorite, who utilized a tight guard to edge the cleaner stanzas.
The audience's tolerance diminished during constant clinching, with Parker slipping to the canvas various instances during close exchanges.
Parker finished the stronger, but multiple periods were difficult to score. Although, former world champion Carl Frampton - providing analysis for Dazn - had it particularly wide for Parker, scoring for Buatsi just a single round.
Buatsi advances, but with the presence of heavy hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the journey to titles - on this evidence - still looks steep.
Hatton Tribute Fuels Local Rivalry Fight
In the co-main event, Arthur overcame Bradley Rea by split-decision in a outstanding Manchester vs Manchester fight to secure the European light heavyweight belt.
The venue fell silent for a profoundly moving tribute prior to the bout as ten bells tolled in remembrance of local hero Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast fight night in the location since Hatton's death. As the concluding sound disappeared, the stillness became a chant of "there's only one Hatton".
The action within the ring reflected the sentiment. The eventual winner was sent to the canvas by a left hook flush on the face in the second round, getting up unsteadily to his footing on the eight count.
But the red-colored attire of Arthur soon advanced again. On the opposite side, the opponent - in rival City blue - was injured early, significant bruising forming under his orbital area as the fighters landed powerful shots.
The challenger, 27, connected with strong blows but the champion, 34, matched the intensity with powerful upward punches as the intensity rarely dropped over twelve rounds.
The victor narrowly won the result with scoring tallies of draw, 115-113 and clearer margin, but the two athletes were persistent and full of heart, exactly what their idol Hatton stood for.
