UK light heavyweight Buatsi earned a win yet disappointing debut to life under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a majority decision in a tight 10-round contest at the Manchester venue.
But Parker landed significant shots, landing some telling clean blows in a fight where the approaches failed to mesh, with excessive holding disrupting the action.
Two judges judged it 96-94 for to the winner, with the final judge a even score.
"It wasn't my greatest showing but what do champions do? They succeed," Buatsi said in the ring as he was met by disapproval from the spectators.
The Londoner returned to winning ways after his maiden career setback - an epic battle with Callum Smith in February - to claim a 20th pro success.
Various analysts felt Parker, 31, should have been awarded the victory but the British boxer suffered the second setback of his 28-fight career.
Buatsi Earns Win in Dull Match
The fighter's advancement has stalled in recent years through promotional disputes and long spells of inactivity.
Earlier forecast as the next star of UK boxing, he now is positioned trying to realize his potential - perhaps in what feels like a ultimate opportunity - under fresh management.
He opened tentatively, with both competitors willing to be aggressive in a cagey early stages.
Parker, whose sole prior loss came at super middleweight against John Ryder in 2022 after suffering a hand injury mid-fight, was making just his second appearance at the higher weight class.
By the halfway stage, Parker had kept it close, causing problems for Buatsi, who worked behind a solid defense to narrowly win the cleaner stanzas.
The crowd's patience decreased amid constant clinching, with Parker falling to the floor several times during close exchanges.
Parker finished the stronger, but several stanzas were challenging to assess. Nevertheless, former world champion the boxing analyst - working with the broadcast network - had it significantly in favor for the challenger, giving Buatsi just one round.
The victor progresses, but with the caliber of heavy hitter Benavidez, and Russian star Bivol ruling the division, the path to championship success - based on this performance - still appears challenging.
Hatton Homage Inspires Manchester Derby Contest
In the supporting bout, Lyndon Arthur beat Bradley Rea by split-decision in a terrific local rivalry contest to win the continental belt.
The stadium became quiet for a deeply poignant homage before the fight as ten bells tolled in memory of local hero Ricky Hatton, who passed away aged 46 in recently.
It was the initial significant broadcast match card in the location since Hatton's passing. As the concluding sound ended, the stillness gave way to a shout of "there's only one Hatton".
The competition inside the ropes equaled the feeling. Arthur was floored by a powerful punch directly to the jaw in the initial stage, getting up unsteadily to his footing on the referee's count.
But the traditional red shorts of Arthur soon advanced again. From the other corner, the opponent - in competitive blue - was marked up soon, heavy swelling developing under his face as the fighters traded hard punches.
Rea, 27, delivered effective strikes but Arthur, 34, matched the intensity with powerful upward punches as the action seldom decreased over the full distance.
The victor edged the decision with scoring tallies of 114-114, close margin and wider gap, but both fighters were determined and brave, everything their idol the legend embodied.
