UK light heavyweight Buatsi made a winning yet disappointing debut to his career under fresh promotional backing with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a close ten-round bout at the Co-op Live Arena.
But Parker found success, landing some telling individual punches in a match where the styles never quite clicked, with frequent clinching disrupting the contest.
The officials scored it 96-94 to the winner, with the final judge a even score.
"It wasn't my finest performance but what do champions do? They win," the victor stated in the ringside as he was faced boos from the crowd.
The Londoner bounced back after his maiden career setback - an thrilling contest with his previous opponent in February - to claim a twentieth professional win.
Several boxing experts felt Parker, thirty-one, deserved the win but the Derbyshire fighter suffered the second defeat of his 28-bout professional journey.
Buatsi Earns Win in Uneventful Encounter
His career development has stalled in the past few years through management issues and extended periods of lack of fights.
Previously predicted as the rising talent of British boxing, he now is positioned trying to achieve expectations - maybe in what feels like a last chance - under new promotional backing.
He began cautiously, with neither fighter prepared to overcommit in a calculated initial rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after breaking his hand mid-fight, was participating in his second appearance at the higher weight class.
By the middle rounds, Parker had kept it close, causing problems for Buatsi, who worked behind a protective stance to edge the cleaner periods.
The audience's tolerance decreased amid regular grabbing, with the challenger slipping to the canvas various instances during grappling.
The underdog closed well, but many rounds were hard to judge. Although, previous titleholder Carl Frampton - commentating on Dazn - had it significantly in favor for the challenger, awarding Buatsi just one round.
The victor moves on, but with the likes of power puncher David Benavidez, and Russian champion Bivol dominating the weight class, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Memorial Fuels Local Rivalry Contest
In the co-main event, Lyndon Arthur beat Rea by close verdict in a excellent local rivalry fight to win the European light heavyweight championship.
The stadium fell silent for a extremely emotional memorial prior to the bout as a bell ceremony sounded in honor of the city's native Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast boxing event in the location since Hatton's passing. As the final chime ended, the quiet gave way to a shout of "there's just one Hatton".
The fighting during the bout equaled the feeling. The eventual winner was floored by a powerful punch squarely on the face in the second round, rising shakily to his feet on the eight count.
But the red-colored attire of the fighter soon pressed ahead again. On the opposite side, Rea - in competitive blue - was marked up quickly, heavy swelling forming under his face as the duo landed powerful shots.
The challenger, 27, landed power punches but the champion, 34, responded in kind with powerful upward punches as the action hardly diminished over the full distance.
The victor edged the decision with judges scorecards of 114-114, close margin and 115-112, but the two athletes were persistent and brave, everything their hero the legend embodied.
