British light-heavyweight Buatsi earned a win yet underwhelming start to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output likely gained him a majority decision in a tight ten-round fight at the Manchester venue.
But Parker had his moments, landing some telling clean blows in a contest where the approaches failed to mesh, with excessive holding spoiling the contest.
The scoring judges scored it 96-94 in favor to Buatsi, with the third a 95-95 draw.
"It wasn't my greatest performance but how do champions respond? They prevail," Buatsi stated in the ring as he was faced negative reactions from the spectators.
The British fighter bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to claim a 20th pro success.
Several boxing experts felt the challenger, 31, merited the victory but the Derbyshire fighter endured the second loss of his 28-fight professional journey.
Buatsi Earns Win in Dull Encounter
The fighter's advancement has slowed in the past few years through contract problems and extended periods of lack of fights.
Once tipped as the future of the British fight scene, he now finds himself trying to realize his potential - perhaps in what seems like a ultimate opportunity - under new promotional backing.
He opened tentatively, with neither fighter ready to overcommit in a calculated initial rounds.
The challenger, whose single earlier setback came at super-middleweight against his former opponent in 2022 after damaging his hand during the bout, was competing in only his second appearance at light heavyweight.
By the middle rounds, the underdog had kept it close, creating difficulties for the favorite, who utilized a protective stance to barely take the better periods.
The spectators' acceptance wore thin because of regular grabbing, with Parker going down various instances during close exchanges.
The underdog ended stronger, but several stanzas were hard to judge. However, previous titleholder Carl Frampton - commentating on Dazn - had it significantly in favor for Parker, giving Buatsi just only one stanza.
Buatsi progresses, but with the presence of power puncher Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - based on this performance - still looks steep.
Hatton Homage Fuels Local Rivalry Battle
In the supporting bout, Lyndon Arthur beat Rea by split-decision in a outstanding local rivalry fight to secure the European light heavyweight belt.
The arena fell silent for a deeply poignant memorial before the fight as 10 bells tolled in memory of Manchester's own Ricky Hatton, who succumbed at age 46 in September.
It was the first major televised match card in the city since Hatton's passing. As the final chime ended, the stillness gave way to a chant of "there's just one Ricky Hatton".
The competition inside the ropes reflected the feeling. Arthur was sent to the canvas by a powerful punch flush on the jaw in the second round, getting up unsteadily to his feet on the referee's count.
But the traditional red attire of the fighter soon advanced again. Across the ring, the opponent - in opposing blue - was marked up soon, significant bruising appearing under his orbital area as the fighters traded powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, responded in kind with powerful upward punches as the intensity rarely dropped over twelve rounds.
The victor edged the verdict with official scores of even score, close margin and wider gap, but the two athletes were relentless and brave, all the qualities their inspiration the legend stood for.
