UK light heavyweight Buatsi secured a victory yet unimpressive beginning to life under recent management with a points victory over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a judges' verdict in a tight ten-round fight at the boxing arena.
But the challenger had his moments, connecting with powerful individual punches in a fight where the approaches failed to mesh, with excessive holding disrupting the fight.
The officials scored it 96-94 for to the winner, with the third a 95-95.
"It wasn't my finest display but how do champions respond? They succeed," the victor said in the arena as he was greeted with negative reactions from the spectators.
The Londoner returned to winning ways after his maiden career setback - an memorable fight with Callum Smith in February - to secure a 20th pro success.
Various analysts believed the challenger, thirty-one, should have been awarded the win but the Derbyshire fighter suffered the second loss of his 28-match career.
The Champion Earns Triumph in Uneventful Encounter
The fighter's advancement has plateaued in recent times through promotional disputes and considerable time of lack of fights.
Once tipped as the future of British boxing, he now is positioned trying to fulfil that early promise - possibly in what feels like a final roll of the dice - under fresh management.
He began cautiously, with neither fighter willing to be aggressive in a cagey initial rounds.
Parker, whose only previous defeat came at super-middleweight against John Ryder in 2022 after breaking his hand in the contest, was participating in his second fight at light-heavyweight.
By the fight's midpoint, Parker had made it competitive, creating difficulties for the favorite, who worked behind a solid defense to edge the more effective stanzas.
The spectators' acceptance diminished because of regular grabbing, with Parker slipping to the canvas several times during grappling.
Parker ended stronger, but several stanzas were challenging to assess. Although, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
The victor moves on, but with the presence of heavy hitter Benavidez, and Russian champion Bivol dominating the weight class, the path to championship success - based on this performance - still appears challenging.
Hatton Homage Fuels All-Manchester Contest
In the supporting bout, Lyndon Arthur overcame Rea by close verdict in a excellent all-Manchester battle to secure the European light-heavyweight title.
The venue fell silent for a profoundly moving memorial ahead of the contest as 10 bells rang in honor of local hero Ricky Hatton, who succumbed 46 years old in last month.
It was the first major televised match card in the urban center since the passing of Hatton. As the concluding sound faded, the stillness gave way to a shout of "only one Hatton".
The fighting within the ring matched the emotion. Arthur was sent to the canvas by a left hook flush on the chin in the initial stage, standing uncertainly to his position on the eight count.
But the red-colored equipment of the fighter soon advanced again. From the other corner, the opponent - in competitive blue - was marked up early, significant bruising developing under his orbital area as the duo exchanged punishing blows.
The challenger, twenty-seven, connected with strong blows but the champion, 34, fought fire with fire with powerful upward punches as the pace hardly diminished over 12 rounds.
Arthur edged the verdict with judges scorecards of 114-114, narrow lead and wider gap, but the two athletes were determined and full of heart, exactly what their idol the legend represented.
