British light-heavyweight Buatsi made a winning yet underwhelming start to life under recent management with a points victory over Zach Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a split decision in a close ten-round fight at the boxing arena.
But Parker landed significant shots, delivering effective individual punches in a fight where the styles never quite clicked, with frequent clinching spoiling the fight.
The officials scored it 96-94 to the winner, with the remaining official a 95-95 draw.
"It wasn't my best showing but what defines champions? They prevail," Buatsi commented in the arena as he was faced boos from the spectators.
The Londoner bounced back after his maiden career setback - an thrilling contest with his previous opponent in last winter - to claim a 20th career victory.
Various analysts believed the challenger, thirty-one, deserved the win but the Derbyshire fighter suffered the second defeat of his 28-fight career.
The Champion Claims Win in Dull Match
Buatsi's progress has stalled in recent years 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 - possibly in what feels like a last chance - under fresh management.
He opened tentatively, with both competitors willing to take risks in a calculated opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand in the contest, was making just his second appearance at the higher weight class.
By the fight's midpoint, Parker had kept it close, causing problems for the favorite, who utilized a protective stance to barely take the more effective stanzas.
The audience's tolerance decreased amid regular grabbing, with the challenger falling to the floor various instances during grappling.
Parker closed well, but multiple periods were difficult to score. Although, previous titleholder Carl Frampton - working with Dazn - had it significantly in favor for Parker, giving Buatsi just only one stanza.
Buatsi moves on, but with the presence of heavy hitter Benavidez, and Russian champion Bivol leading the category, the path to championship success - based on this performance - still seems difficult.
Ricky Hatton Tribute Motivates Manchester Derby Battle
In the co-main event, Lyndon Arthur defeated Bradley Rea by split-decision in a terrific all-Manchester battle to secure the European light heavyweight championship.
The stadium fell silent for a extremely emotional memorial ahead of the contest as a bell ceremony sounded in memory of the city's native Hatton, who succumbed aged 46 in last month.
It was the first major televised fight night in the urban center since Hatton's death. As the last bell faded, the stillness became a shout of "only one Hatton".
The fighting during the bout reflected the sentiment. Arthur was sent to the canvas by a significant blow directly to the jaw in the second round, rising shakily to his footing on the referee's count.
But the traditional red shorts of Arthur soon advanced again. On the opposite side, Rea - in competitive blue - was marked up quickly, significant bruising developing under his eye as the duo landed powerful shots.
Rea, twenty-seven, landed power punches but the champion, 34, fought fire with fire with stinging uppercuts as the action seldom decreased over the full distance.
The victor narrowly won the verdict with official scores of even score, close margin and clearer margin, but the two athletes were determined and courageous, exactly what their idol the legend stood for.
