British light-heavyweight Buatsi earned a win yet disappointing beginning to his career under recent management with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a split decision in a close ten-round fight at the Manchester venue.
But Parker landed significant shots, connecting with powerful clean blows in a match where the approaches didn't complement each other, with constant grabbing marring the action.
The scoring judges scored it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my greatest display but what defines champions? They succeed," the victor commented in the ring as he was faced boos from the crowd.
The British fighter returned to winning ways after his maiden career setback - an thrilling contest with Callum Smith in last winter - to earn a 20th pro success.
Some ringside observers thought the challenger, thirty-one, merited the decision but the Derbyshire fighter suffered the second defeat of his 28-bout career.
Buatsi Claims Triumph in Uneventful Affair
Buatsi's progress has stalled in recent times through management issues and long spells of lack of fights.
Once tipped as the rising talent of UK boxing, he now is positioned trying to fulfil that early promise - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He opened tentatively, with both competitors ready to be aggressive in a cagey initial rounds.
Parker, whose single earlier setback came at the lower weight class against his former opponent in 2022 after breaking his hand in the contest, was competing in only his second fight at light heavyweight.
By the middle rounds, the underdog had kept it close, creating difficulties for the favorite, who worked behind a protective stance to barely take the better rounds.
The audience's tolerance decreased amid frequent holding, with the challenger slipping to the canvas various instances during close exchanges.
Parker finished the stronger, but multiple periods were challenging to assess. Nevertheless, ex-champion Carl Frampton - commentating on Dazn - had it significantly in favor for the challenger, scoring for Buatsi just one round.
The victor progresses, but with the caliber of power puncher Benavidez, and Russian star Bivol dominating the weight class, the journey to titles - on this evidence - still looks steep.
Hatton Homage Motivates All-Manchester Battle
In the secondary fight, Lyndon Arthur overcame Rea by divided decision in a outstanding all-Manchester contest to secure the European light heavyweight belt.
The venue fell silent for a extremely emotional homage before the fight as a bell ceremony tolled in honor of the city's native Hatton, who succumbed 46 years old in last month.
It was the initial significant broadcast boxing event in the urban center since Hatton's passing. As the concluding sound faded, the stillness gave way to a chant of "only one Hatton".
The action during the bout reflected the emotion. Arthur was knocked down by a left hook flush on the chin in the early round, standing uncertainly to his feet on the eight count.
But the traditional red equipment of Arthur soon came forward again. Across the ring, Rea - in rival City blue - was damaged soon, noticeable damage forming under his eye as the fighters landed hard punches.
Rea, 27, delivered effective strikes but the champion, 34, fought fire with fire with stinging uppercuts as the action hardly diminished over the full distance.
The victor barely secured the decision with scoring tallies of 114-114, close margin and wider gap, but the two athletes were determined and courageous, everything their idol Hatton embodied.
