British light-heavyweight Buatsi earned a win yet disappointing beginning to life under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a split decision in a close 10-round contest at the Manchester venue.
But the challenger landed significant shots, landing some telling single shots in a fight where the approaches didn't complement each other, with constant grabbing disrupting the contest.
Two judges had it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my best performance but how do champions respond? They succeed," Buatsi said in the arena as he was greeted with boos from the crowd.
The Londoner returned to winning ways after his maiden career setback - an epic battle with Callum Smith in last winter - to earn a twentieth professional win.
Some ringside observers thought the challenger, thirty-one, deserved the victory but the contender experienced the second setback of his 28-bout professional journey.
Buatsi Secures Win in Dull Match
The fighter's advancement has plateaued in recent years through management issues and long spells of inactivity.
Earlier forecast as the future of British boxing, he now stands trying to achieve expectations - possibly in what feels like a ultimate opportunity - under fresh management.
He opened tentatively, with the two boxers prepared to overcommit in a calculated early stages.
Parker, whose single earlier setback came at super middleweight against his former opponent in two years ago after breaking his hand during the bout, was participating in his second bout at the higher weight class.
By the middle rounds, the underdog had stayed in contention, causing problems for the favorite, who worked behind a solid defense to edge the more effective rounds.
The crowd's patience diminished amid frequent holding, with the challenger slipping to the canvas several times during clinches.
The underdog closed well, but many rounds were challenging to assess. However, ex-champion Carl Frampton - working with Dazn - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
Buatsi advances, but with the caliber of power puncher Benavidez, and Russian star Dmitry Bivol ruling the division, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Homage Inspires All-Manchester Fight
In the co-main event, Arthur defeated Rea by divided decision in a excellent local rivalry battle to secure the European light-heavyweight belt.
The stadium grew hushed for a extremely emotional homage before the fight as ten bells sounded in remembrance of Manchester's own Hatton, who succumbed at age 46 in recently.
It was the first major televised boxing event in the city since the passing of Hatton. As the last bell faded, the silence gave way to a shout of "there's only one Hatton".
The fighting inside the ropes equaled the sentiment. Arthur was floored by a significant blow directly to the chin in the initial stage, getting up unsteadily to his footing on the count of eight.
But the traditional red equipment of Arthur soon advanced again. On the opposite side, Rea - in opposing blue - was marked up quickly, heavy swelling developing under his orbital area as the duo landed hard punches.
Rea, 27, landed power punches but the champion, 34, matched the intensity with powerful upward punches as the action seldom decreased over twelve rounds.
Arthur edged the result with official scores of draw, 115-113 and 115-112, but both fighters were determined and brave, all the qualities their inspiration the legend embodied.
