British light heavyweight Buatsi made a winning yet disappointing start to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a majority decision in a competitive 10-round contest at the boxing arena.
But Parker had his moments, delivering effective single shots in a fight where the approaches failed to mesh, with constant grabbing spoiling the contest.
The officials scored it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my greatest showing but how do champions respond? They prevail," Buatsi commented in the ringside as he was met by boos from the audience.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in February - to earn a twentieth professional win.
Several boxing experts thought Parker, 31, deserved the win but the British boxer experienced the second defeat of his 28-fight professional journey.
Buatsi Secures Triumph in Slow Encounter
Buatsi's progress has stalled in the past few years through management issues and considerable time of inactivity.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to fulfil that early promise - possibly in what appears to be a final roll of the dice - under recent support.
He started carefully, with the two boxers prepared to take risks in a tentative opening few rounds.
The challenger, whose single earlier setback came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was making just his second bout at the higher weight class.
By the fight's midpoint, Parker had made it competitive, creating difficulties for the favorite, who utilized a solid defense to narrowly win the better periods.
The crowd's patience wore thin because of constant clinching, with the challenger going down various instances during grappling.
Parker ended stronger, but many rounds were challenging to assess. Although, previous titleholder Carl Frampton - providing analysis for Dazn - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
The victor advances, but with the presence of heavy hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Tribute Fuels Local Rivalry Battle
In the secondary fight, Lyndon Arthur beat Rea by split-decision in a outstanding local rivalry contest to capture the continental championship.
The arena grew hushed for a deeply poignant tribute ahead of the contest as ten bells tolled in remembrance of local hero Ricky Hatton, who passed away at age 46 in September.
It was the premier televised match card in the location since Hatton's death. As the final chime faded, the stillness gave way to a chant of "there's just one Ricky Hatton".
The fighting during the bout equaled the sentiment. The eventual winner was floored by a powerful punch directly to the face in the initial stage, getting up unsteadily to his position on the referee's count.
But the traditional red shorts of the fighter soon pressed ahead again. From the other corner, Rea - in opposing blue - was damaged soon, heavy swelling developing under his orbital area as the duo landed punishing blows.
Rea, 27, connected with strong blows but Arthur, thirty-four, responded in kind with effective uppercuts as the action hardly diminished over 12 rounds.
The victor barely secured the result with scoring tallies of draw, narrow lead and clearer margin, but the two athletes were relentless and brave, all the qualities their hero Hatton embodied.
