British light heavyweight Buatsi earned a win yet underwhelming start to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a judges' verdict in a tight ten-round bout at the Co-op Live Arena.
But Parker had his moments, connecting with powerful clean blows in a contest where the techniques never quite clicked, with frequent clinching marring the action.
The scoring judges scored it 96-94 in favor to the winner, with the third a even score.
"It wasn't my greatest showing but what defines champions? They succeed," the victor said in the ringside as he was met by negative reactions from the spectators.
The Londoner bounced back after his initial pro loss - an memorable fight with Callum Smith in last winter - to secure a 20th pro success.
Various analysts believed the challenger, 31, should have been awarded the win but the Derbyshire fighter endured the second loss of his 28-bout professional journey.
The Champion Secures Triumph in Dull Match
The fighter's advancement has slowed in the past few years through contract problems and considerable time of inactivity.
Once tipped as the future of the British fight scene, he now is positioned trying to realize his potential - perhaps in what appears to be a last chance - under new promotional backing.
He started carefully, with both competitors prepared to be aggressive in a cagey initial rounds.
The challenger, whose only previous defeat came at the lower weight class against John Ryder in 2022 after damaging his hand in the contest, was making just his second fight at light heavyweight.
By the middle rounds, Parker had stayed in contention, creating difficulties for Buatsi, who operated with a protective stance to barely take the cleaner stanzas.
The crowd's patience wore thin during frequent holding, with the challenger falling to the floor various instances during close exchanges.
The underdog ended stronger, but multiple periods were difficult to score. Nevertheless, ex-champion Carl Frampton - working with Dazn - had it particularly wide for the challenger, giving Buatsi just only one stanza.
The victor advances, but with the likes of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Tribute Fuels All-Manchester Fight
In the secondary fight, Lyndon Arthur overcame Bradley Rea by close verdict in a outstanding local rivalry contest to secure the continental title.
The arena became quiet for a profoundly moving memorial prior to the bout as a bell ceremony tolled in honor of Manchester's own Ricky Hatton, who succumbed aged 46 in September.
It was the first major televised boxing event in the urban center since the passing of Hatton. As the last bell faded, the silence gave way to a shout of "there's only one Ricky Hatton".
The fighting during the bout matched the sentiment. Arthur was sent to the canvas by a left hook squarely on the jaw in the initial stage, rising shakily to his position on the referee's count.
But the red-colored attire of Arthur soon pressed ahead again. On the opposite side, the opponent - in opposing blue - was marked up early, significant bruising developing under his eye as the duo traded punishing blows.
Rea, 27, connected with strong blows but Arthur, 34, fought fire with fire with effective uppercuts as the pace seldom decreased over the full distance.
Arthur barely secured the decision with judges scorecards of draw, narrow lead and 115-112, but the two athletes were relentless and brave, all the qualities their inspiration the legend stood for.
