UK light-heavyweight Buatsi earned a win yet unimpressive beginning to his career under recent management with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output appeared to earn him a judges' verdict in a competitive 10-round fight at the Co-op Live Arena.
But the challenger found success, connecting with powerful individual punches in a fight where the styles failed to mesh, with constant grabbing disrupting the fight.
The scoring judges had it 96-94 in favor to the winner, with the remaining official a even score.
"It wasn't my best performance but what do champions do? They prevail," Buatsi stated in the ring as he was greeted with boos from the crowd.
The Londoner bounced back after his first professional defeat - an memorable fight with his previous opponent in last winter - to secure a 20th pro success.
Some ringside observers felt the challenger, thirty-one, should have been awarded the win but the contender experienced the second defeat of his 28-match professional journey.
The Champion Claims Victory in Slow Match
His career development has plateaued in the past few years through management issues and extended periods of lack of fights.
Once tipped as the next star of British boxing, he now stands trying to achieve expectations - perhaps in what feels like a final roll of the dice - under recent support.
He opened tentatively, with both competitors ready to overcommit in a calculated initial rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in 2022 after breaking his hand during the bout, was making just his second appearance at the higher weight class.
By the halfway stage, the underdog had made it competitive, creating difficulties for the favorite, who operated with a protective stance to barely take the more effective stanzas.
The spectators' acceptance wore thin because of regular grabbing, with the challenger slipping to the canvas various instances during close exchanges.
Parker ended stronger, but many rounds were hard to judge. Nevertheless, previous titleholder the boxing analyst - providing analysis for Dazn - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - judging by this showing - still seems difficult.
Ricky Hatton Tribute Motivates All-Manchester Contest
In the secondary fight, Lyndon Arthur overcame Rea by divided decision in a terrific local rivalry contest to win the continental belt.
The stadium became quiet for a deeply poignant tribute prior to the bout as 10 bells tolled in remembrance of Manchester's own Ricky Hatton, who died 46 years old in recently.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the last bell disappeared, the silence gave way to a roar of "there's only one Hatton".
The competition inside the ropes matched the sentiment. The eventual winner was sent to the canvas by a powerful punch directly to the face in the early round, rising shakily to his feet on the referee's count.
But the Manchester United-red attire of the fighter soon pressed ahead again. From the other corner, Rea - in competitive blue - was injured quickly, noticeable damage forming under his face as the duo traded hard punches.
Rea, 27, landed power punches but Arthur, 34, responded in kind with powerful upward punches as the action seldom decreased over the full distance.
The victor narrowly won the result with judges scorecards of even score, narrow lead and wider gap, but both fighters were relentless and full of heart, everything their inspiration Hatton represented.
