British light heavyweight Buatsi earned a win yet underwhelming start to his career under new promoters with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a judges' verdict in a tight ten-round bout at the Manchester venue.
But Parker found success, landing some telling individual punches in a fight where the styles failed to mesh, with excessive holding spoiling the action.
The scoring judges judged it 96-94 in favor to Buatsi, with the remaining official a even score.
"It wasn't my best showing but what defines champions? They prevail," Buatsi said in the arena as he was faced disapproval from the crowd.
The British fighter returned to winning ways after his initial pro loss - an epic battle with his previous opponent in February - to claim a 20th career victory.
Various analysts thought Parker, thirty-one, should have been awarded the decision but the contender experienced the second defeat of his 28-bout professional journey.
Buatsi Earns Win in Slow Match
His career development has stalled in recent times through management issues and considerable time of inactivity.
Once tipped as the next star of the British fight scene, he now stands trying to achieve expectations - maybe in what seems like a last chance - under new promotional backing.
He began cautiously, with neither fighter willing to be aggressive in a tentative initial rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in 2022 after damaging his hand in the contest, was making just his second bout at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for Buatsi, who utilized a tight guard to narrowly win the cleaner stanzas.
The spectators' acceptance diminished because of frequent holding, with Parker falling to the floor various instances during grappling.
The underdog ended stronger, but several stanzas were challenging to assess. Nevertheless, ex-champion the boxing analyst - working with the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
The victor advances, but with the presence of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Homage Fuels Manchester Derby Fight
In the supporting bout, Lyndon Arthur overcame Rea by split-decision in a outstanding Manchester vs Manchester fight to secure the European light-heavyweight title.
The arena grew hushed for a extremely emotional tribute before the fight as a bell ceremony rang in honor of local hero Ricky Hatton, who passed away at age 46 in September.
It was the premier televised fight night in the city since Hatton's death. As the concluding sound ended, the quiet gave way to a roar of "only one Ricky Hatton".
The fighting inside the ropes reflected the feeling. Arthur was sent to the canvas by a significant blow flush on the face in the early round, rising shakily to his position on the referee's count.
But the red-colored equipment of the fighter soon came forward again. On the opposite side, the opponent - in competitive blue - was damaged quickly, heavy swelling developing under his orbital area as the fighters landed punishing blows.
Rea, 27, delivered effective strikes but Arthur, 34, responded in kind with stinging uppercuts as the intensity hardly diminished over twelve rounds.
The victor barely secured the decision with official scores of draw, 115-113 and clearer margin, but each competitor were relentless and full of heart, all the qualities their idol Hatton represented.
