British light heavyweight Buatsi earned a win yet unimpressive start to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a majority decision in a competitive 10-round bout at the boxing arena.
But Parker had his moments, delivering effective individual punches in a match where the approaches never quite clicked, with constant grabbing disrupting the contest.
The officials judged it 96-94 in favor to the winner, with the remaining official a 95-95.
"It wasn't my best performance but what do champions do? They prevail," the victor said in the arena as he was faced disapproval from the spectators.
The Londoner bounced back after his initial pro loss - an memorable fight with Callum Smith in February - to claim a 20th career victory.
Some ringside observers thought Parker, 31, should have been awarded the victory but the Derbyshire fighter endured the second setback of his 28-match professional journey.
Buatsi Earns Triumph in Dull Encounter
The fighter's advancement has slowed in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the future of British boxing, he now finds himself trying to realize his potential - possibly in what seems like a last chance - under fresh management.
He began cautiously, with neither fighter ready to be aggressive in a calculated initial rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in two years ago after suffering a hand injury during the bout, was competing in only his second appearance at the higher weight class.
By the halfway stage, the underdog had made it competitive, creating difficulties for Buatsi, who utilized a tight guard to barely take the better stanzas.
The crowd's patience wore thin amid regular grabbing, with the challenger slipping to the canvas several times during grappling.
The underdog finished the stronger, but many rounds were challenging to assess. However, ex-champion Carl Frampton - commentating on the broadcast network - had it strongly leaning for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the likes of power puncher Benavidez, and Russian champion Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Hatton Memorial Inspires All-Manchester Battle
In the secondary fight, Lyndon Arthur beat Bradley Rea by close verdict in a excellent Manchester vs Manchester contest to capture the continental belt.
The stadium grew hushed for a profoundly moving homage before the fight as a bell ceremony rang in honor of local hero Hatton, who died at age 46 in recently.
It was the initial significant broadcast match card in the location since the passing of Hatton. As the last bell faded, the silence transitioned to a roar of "there's just one Hatton".
The action during the bout reflected the feeling. The eventual winner was knocked down by a left hook directly to the jaw in the second round, rising shakily to his feet on the eight count.
But the traditional red shorts of the fighter soon advanced again. Across the ring, the opponent - in rival City blue - was damaged soon, noticeable damage forming under his eye as the fighters exchanged punishing blows.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace rarely dropped over the full distance.
Arthur barely secured the decision with judges scorecards of even score, narrow lead and wider gap, but each competitor were relentless and brave, exactly what their inspiration Hatton stood for.
