British light-heavyweight Buatsi earned a win yet disappointing start to his career under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's punch output likely gained him a split decision in a competitive ten-round fight at the boxing arena.
But Parker found success, delivering effective clean blows in a contest where the approaches failed to mesh, with frequent clinching marring the fight.
The officials had it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my best performance but what do champions do? They prevail," the victor commented in the ring as he was faced boos from the crowd.
The British fighter bounced back after his maiden career setback - an memorable fight with Callum Smith in last winter - to secure a twentieth professional win.
Some ringside observers felt Parker, 31, should have been awarded the decision but the contender suffered the second setback of his 28-bout career.
His career development has stalled in recent times through promotional disputes and considerable time of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now finds himself trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under fresh management.
He began cautiously, with neither fighter willing to take risks in a calculated initial rounds.
Parker, whose single earlier setback came at super-middleweight against his former opponent in 2022 after damaging his hand during the bout, was making just his second bout at the higher weight class.
By the middle rounds, the underdog had kept it close, making life awkward for Buatsi, who operated with a tight guard to narrowly win the more effective periods.
The spectators' acceptance diminished because of frequent holding, with Parker slipping to the canvas multiple occasions during grappling.
Parker closed well, but several stanzas were challenging to assess. Although, former world champion Carl Frampton - working with the broadcast network - had it significantly in favor for the challenger, giving Buatsi just only one stanza.
Buatsi advances, but with the presence of power puncher Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - judging by this showing - still looks steep.
In the secondary fight, Arthur defeated Bradley Rea by divided decision in a terrific Manchester vs Manchester contest to capture the continental title.
The arena fell silent for a extremely emotional homage ahead of the contest as ten bells tolled in honor of Manchester's own Ricky Hatton, who died aged 46 in recently.
It was the first major televised match card in the location since Hatton's passing. As the final chime disappeared, the quiet transitioned to a roar of "only one Ricky Hatton".
The fighting during the bout matched the emotion. Arthur was floored by a powerful punch flush on the jaw in the second round, standing uncertainly to his feet on the referee's count.
But the Manchester United-red shorts of Arthur soon pressed ahead again. On the opposite side, the opponent - in rival City blue - was marked up early, significant bruising forming under his orbital area as the duo landed punishing blows.
The challenger, twenty-seven, landed power punches but the champion, 34, fought fire with fire with powerful upward punches as the action hardly diminished over the full distance.
The victor barely secured the result with official scores of draw, narrow lead and 115-112, but the two athletes were determined and courageous, all the qualities their inspiration Hatton embodied.
Liam is a seasoned sports analyst with over a decade of experience in odds modeling and betting strategy.