UK light heavyweight Buatsi secured a victory yet underwhelming debut to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a competitive 10-round bout at the Co-op Live Arena.
But the challenger landed significant shots, connecting with powerful single shots in a fight where the techniques didn't complement each other, with constant grabbing spoiling the action.
The scoring judges scored it 96-94 in favor to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best performance but how do champions respond? They win," Buatsi stated in the arena as he was greeted with disapproval from the crowd.
The Londoner bounced back after his first professional defeat - an epic battle with Callum Smith in last winter - to claim a 20th career victory.
Some ringside observers felt Parker, 31, merited the win but the contender suffered the second defeat of his 28-match professional journey.
Buatsi Earns Win in Dull Affair
Buatsi's progress has slowed in recent years through management issues and considerable time of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now is positioned trying to achieve expectations - maybe in what appears to be a ultimate opportunity - under fresh management.
He started carefully, with both competitors willing to overcommit in a cagey early stages.
The challenger, whose sole prior loss came at the lower weight class against John Ryder in 2022 after breaking his hand mid-fight, was competing in only his second appearance at the higher weight class.
By the middle rounds, the underdog had kept it close, causing problems for Buatsi, who utilized a tight guard to edge the more effective rounds.
The crowd's patience wore thin amid regular grabbing, with the challenger going down several times during grappling.
The underdog closed well, but multiple periods were challenging to assess. Although, former world champion the boxing analyst - providing analysis for Dazn - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
Buatsi progresses, but with the presence of power puncher Benavidez, and Russian champion Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Memorial Fuels All-Manchester Battle
In the co-main event, Arthur overcame Bradley Rea by close verdict in a excellent local rivalry contest to secure the European light heavyweight belt.
The venue fell silent for a deeply poignant memorial ahead of the contest as ten bells rang in memory of Manchester's own Hatton, who died aged 46 in recently.
It was the initial significant broadcast match card in the location since Hatton's passing. As the final chime ended, the silence gave way to a chant of "only one Ricky Hatton".
The fighting during the bout equaled the emotion. Arthur was knocked down by a powerful punch flush on the chin in the initial stage, getting up unsteadily to his feet on the eight count.
But the red-colored shorts of Arthur soon pressed ahead again. On the opposite side, the opponent - in competitive blue - was damaged soon, significant bruising forming under his face as the duo traded punishing blows.
Rea, 27, delivered effective strikes but Arthur, 34, fought fire with fire with effective uppercuts as the action seldom decreased over twelve rounds.
The victor narrowly won the verdict with official scores of even score, 115-113 and clearer margin, but both fighters were relentless and full of heart, everything their hero the legend represented.
