British light-heavyweight Buatsi made a winning yet disappointing debut to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a split decision in a close 10-round fight at the boxing arena.
But the challenger had his moments, landing some telling clean blows in a match where the techniques failed to mesh, with excessive holding marring the action.
The officials had it 96-94 in favor to Buatsi, with the remaining official a 95-95.
"It wasn't my best display but how do champions respond? They prevail," Buatsi said in the ringside as he was met by disapproval from the crowd.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in February - to claim a 20th pro success.
Various analysts felt Parker, thirty-one, merited the decision but the Derbyshire fighter suffered the second loss of his 28-match professional journey.
The Champion Earns Win in Slow Encounter
Buatsi's progress has plateaued in recent times through management issues and long spells of inactivity.
Earlier forecast as the next star of British boxing, he now finds himself trying to achieve expectations - possibly in what feels like a last chance - under recent support.
He opened tentatively, with neither fighter ready to overcommit in a tentative opening few rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand during the bout, was making just his second fight at the higher weight class.
By the fight's midpoint, Parker had stayed in contention, causing problems for the favorite, who worked behind a solid defense to barely take the cleaner rounds.
The crowd's patience decreased during frequent holding, with the challenger going down various instances during close exchanges.
The underdog closed well, but many rounds were challenging to assess. Nevertheless, previous titleholder the boxing analyst - providing analysis for Dazn - had it strongly leaning for Parker, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the presence of power puncher Benavidez, and Russian champion Dmitry Bivol leading the category, the path to championship success - judging by this showing - still appears challenging.
Hatton Memorial Inspires Manchester Derby Battle
In the secondary fight, Lyndon Arthur defeated Bradley Rea by divided decision in a outstanding Manchester vs Manchester fight to secure the continental belt.
The arena grew hushed for a deeply poignant memorial before the fight as ten bells rang in memory of Manchester's own Hatton, who died aged 46 in last month.
It was the premier televised match card in the location since the passing of Hatton. As the last bell ended, the stillness became a chant of "there's only one Hatton".
The competition inside the ropes matched the feeling. Arthur was knocked down by a significant blow flush on the chin in the initial stage, getting up unsteadily to his footing on the eight count.
But the red-colored attire of Arthur soon advanced again. On the opposite side, Rea - in rival City blue - was damaged quickly, significant bruising forming under his orbital area as the fighters exchanged hard punches.
The challenger, 27, delivered effective strikes but Arthur, thirty-four, matched the intensity with effective uppercuts as the action hardly diminished over twelve rounds.
Arthur edged the result with official scores of even score, narrow lead and wider gap, but each competitor were relentless and brave, all the qualities their inspiration Hatton stood for.
