British light-heavyweight Buatsi earned a win yet disappointing beginning to life under fresh promotional backing with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a judges' verdict in a tight ten-round contest at the boxing arena.
But the challenger found success, delivering effective single shots in a contest where the techniques didn't complement each other, with constant grabbing disrupting the contest.
Two judges judged it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my finest performance but what defines champions? They prevail," Buatsi said in the arena as he was met by boos from the spectators.
The British fighter got back to winning after his initial pro loss - an epic battle with Callum Smith in February - to claim a 20th pro success.
Several boxing experts thought the challenger, thirty-one, deserved the victory but the Derbyshire fighter suffered the second defeat of his 28-bout career.
The Champion Secures Victory in Dull Match
His career development has stalled in the past few years through promotional disputes and long spells of lack of fights.
Once tipped as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what seems like a final roll of the dice - under fresh management.
He opened tentatively, with neither fighter ready to overcommit in a calculated opening few rounds.
The challenger, whose sole prior loss came at super middleweight against his former opponent in 2022 after breaking his hand mid-fight, was competing in only his second bout at light-heavyweight.
By the halfway stage, Parker had stayed in contention, creating difficulties for the favorite, who worked behind a solid defense to barely take the cleaner rounds.
The spectators' acceptance diminished because of frequent holding, with Parker slipping to the canvas various instances during close exchanges.
The underdog finished the stronger, but many rounds were challenging to assess. Nevertheless, ex-champion Carl Frampton - working with Dazn - had it particularly wide for Parker, awarding Buatsi just only one stanza.
Buatsi advances, but with the caliber of heavy hitter Benavidez, and Russian star Bivol dominating the weight class, the journey to titles - based on this performance - still seems difficult.
Hatton Homage Inspires Local Rivalry Contest
In the secondary fight, Lyndon Arthur beat Rea by close verdict in a outstanding Manchester vs Manchester contest to capture the European light heavyweight title.
The stadium became quiet for a deeply poignant memorial before the fight as 10 bells tolled in remembrance of local hero Hatton, who died at age 46 in recently.
It was the premier televised boxing event in the urban center since the passing of Hatton. As the last bell disappeared, the silence gave way to a chant of "there's only one Hatton".
The action during the bout reflected the feeling. Arthur was sent to the canvas by a powerful punch squarely on the face in the early round, getting up unsteadily to his position on the count of eight.
But the red-colored attire of the fighter soon advanced again. On the opposite side, the opponent - in competitive blue - was marked up quickly, significant bruising forming under his orbital area as the pair exchanged hard punches.
Rea, twenty-seven, landed power punches but the champion, 34, responded in kind with effective uppercuts as the action hardly diminished over the full distance.
The victor edged the result with judges scorecards of 114-114, 115-113 and clearer margin, but each competitor were determined and full of heart, exactly what their hero the legend represented.
