British light heavyweight Buatsi made a winning yet unimpressive debut to life under fresh promotional backing with a unanimous decision over Zach Parker in Manchester.
The Olympic medal winner's work rate likely gained him a judges' verdict in a competitive ten-round fight at the boxing arena.
But Parker had his moments, delivering effective individual punches in a contest where the techniques failed to mesh, with frequent clinching spoiling the fight.
Two judges judged it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They win," Buatsi commented in the ring as he was met by negative reactions from the spectators.
The British fighter got back to winning after his initial pro loss - an memorable fight with his previous opponent in February - to earn a 20th career victory.
Some ringside observers felt the challenger, 31, deserved the victory but the British boxer suffered the second loss of his 28-fight professional journey.
The Champion Claims Victory in Dull Match
Buatsi's progress has stalled in the past few years through management issues and considerable time of inactivity.
Once tipped as the next star of British boxing, he now finds himself trying to achieve expectations - perhaps in what seems like a ultimate opportunity - under fresh management.
He opened tentatively, with neither fighter prepared to overcommit in a tentative initial rounds.
The challenger, whose sole prior loss came at super-middleweight against his former opponent in 2022 after suffering a hand injury during the bout, was making just his second appearance at light heavyweight.
By the middle rounds, the underdog had stayed in contention, creating difficulties for Buatsi, who worked behind a protective stance to barely take the more effective rounds.
The crowd's patience diminished amid regular grabbing, with the challenger slipping to the canvas various instances during grappling.
Parker ended stronger, but multiple periods were challenging to assess. Nevertheless, former world champion Carl Frampton - working with the broadcast network - had it strongly leaning for Parker, scoring for Buatsi just one round.
Buatsi advances, but with the presence of hard hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the path to championship success - judging by this showing - still seems difficult.
Hatton Memorial Motivates All-Manchester Battle
In the secondary fight, Lyndon Arthur overcame Bradley Rea by close verdict in a outstanding Manchester vs Manchester contest to win the European light-heavyweight belt.
The arena grew hushed for a extremely emotional memorial before the fight as a bell ceremony tolled in remembrance of Manchester's own Ricky Hatton, who succumbed 46 years old in last month.
It was the premier televised boxing event in the location since the passing of Hatton. As the final chime ended, the quiet gave way to a roar of "there's just one Hatton".
The competition inside the ropes equaled the sentiment. Arthur was sent to the canvas by a left hook flush on the face in the early round, rising shakily to his position on the referee's count.
But the red-colored attire of Arthur soon advanced again. From the other corner, the opponent - in competitive blue - was damaged quickly, significant bruising appearing under his orbital area as the fighters traded powerful shots.
The challenger, twenty-seven, landed power punches but Arthur, 34, matched the intensity with powerful upward punches as the intensity hardly diminished over twelve rounds.
The victor edged the verdict with judges scorecards of even score, narrow lead and 115-112, but each competitor were persistent and full of heart, all the qualities their idol Hatton embodied.
