British light heavyweight Buatsi earned a win yet underwhelming start to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a split decision in a close ten-round fight at the boxing arena.
But Parker found success, connecting with powerful individual punches in a fight where the techniques never quite clicked, with frequent clinching spoiling the contest.
The scoring judges judged it 96-94 for to the winner, with the remaining official a even score.
"It wasn't my finest showing but what do champions do? They prevail," Buatsi said in the ringside as he was met by negative reactions from the spectators.
The Londoner got back to winning after his maiden career setback - an memorable fight with Callum Smith in last winter - to secure a 20th career victory.
Various analysts felt Parker, 31, merited the victory but the Derbyshire fighter endured the second defeat of his 28-fight professional journey.
The Champion Claims Win in Slow Encounter
His career development has stalled in recent years through management issues and considerable time of lack of fights.
Previously predicted as the next star of UK boxing, he now stands trying to achieve expectations - perhaps in what appears to be a final roll of the dice - under recent support.
He began cautiously, with neither fighter ready to overcommit in a calculated early stages.
Parker, whose only previous defeat came at super-middleweight against his former opponent in two years ago after breaking his hand during the bout, was competing in only his second fight at light heavyweight.
By the middle rounds, the underdog had kept it close, causing problems for Buatsi, who utilized a solid defense to narrowly win the cleaner rounds.
The audience's tolerance decreased because of constant clinching, with Parker going down multiple occasions during close exchanges.
The underdog ended stronger, but several stanzas were challenging to assess. Although, ex-champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for Parker, giving Buatsi just a single round.
Buatsi moves on, but with the likes of power puncher Benavidez, and Russian champion Bivol leading the category, the path to championship success - based on this performance - still looks steep.
Ricky Hatton Memorial Inspires All-Manchester Battle
In the supporting bout, Arthur beat Rea by divided decision in a excellent local rivalry contest to secure the continental belt.
The stadium became quiet for a deeply poignant tribute ahead of the contest as ten bells rang in remembrance of Manchester's own Hatton, who passed away aged 46 in September.
It was the initial significant broadcast fight night in the urban center since Hatton's death. As the concluding sound ended, the quiet transitioned to a shout of "there's just one Ricky Hatton".
The action during the bout reflected the feeling. The eventual winner was floored by a significant blow flush on the face in the second round, rising shakily to his footing on the count of eight.
But the traditional red equipment of Arthur soon pressed ahead again. From the other corner, the opponent - in opposing blue - was injured quickly, noticeable damage forming under his eye as the duo landed hard punches.
Rea, 27, delivered effective strikes but the champion, 34, matched the intensity with powerful upward punches as the action hardly diminished over twelve rounds.
Arthur edged the decision with judges scorecards of 114-114, narrow lead and 115-112, but both fighters were relentless and courageous, everything their inspiration Hatton stood for.
