British light-heavyweight Buatsi made a winning yet underwhelming debut to life under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output seemingly secured him a judges' verdict in a competitive ten-round fight at the Manchester venue.
But the challenger found success, delivering effective single shots in a fight where the styles didn't complement each other, with excessive holding marring the fight.
The scoring judges judged it 96-94 for to the winner, with the remaining official a 95-95 draw.
"It wasn't my best performance but how do champions respond? They prevail," Buatsi said in the ring as he was faced disapproval from the audience.
The British fighter got back to winning after his first professional defeat - an epic battle with Callum Smith in February - to earn a 20th career victory.
Several boxing experts believed the challenger, 31, merited the victory but the British boxer suffered the second setback of his 28-fight career.
The Champion Claims Victory in Dull Match
His career development has slowed in recent years through management issues and long spells of inactivity.
Previously predicted as the rising talent of UK boxing, he now is positioned trying to realize his potential - perhaps in what feels like a ultimate opportunity - under recent support.
He began cautiously, with neither fighter willing to overcommit in a calculated initial rounds.
Parker, whose sole prior loss came at the lower weight class against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second bout at the higher weight class.
By the middle rounds, Parker had kept it close, causing problems for the favorite, who worked behind a solid defense to barely take the cleaner stanzas.
The crowd's patience wore thin because of regular grabbing, with Parker slipping to the canvas several times during clinches.
Parker ended stronger, but many rounds were difficult to score. Although, former world champion the boxing analyst - working with Dazn - had it particularly wide for Parker, giving Buatsi just a single round.
The victor moves on, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Bivol ruling the division, the road to world glory - based on this performance - still looks steep.
Hatton Tribute Inspires Manchester Derby Battle
In the co-main event, Lyndon Arthur overcame Rea by close verdict in a outstanding Manchester vs Manchester contest to capture the continental belt.
The arena became quiet for a deeply poignant memorial prior to the bout as 10 bells sounded in remembrance of the city's native Ricky Hatton, who passed away at age 46 in September.
It was the first major televised match card in the location since Hatton's death. As the last bell ended, the quiet transitioned to a shout of "there's just one Hatton".
The competition during the bout matched the feeling. Arthur was floored by a left hook directly to the jaw in the second round, getting up unsteadily to his footing on the referee's count.
But the traditional red equipment of the fighter soon came forward again. From the other corner, Rea - in opposing blue - was injured quickly, heavy swelling appearing under his eye as the duo landed powerful shots.
The challenger, twenty-seven, connected with strong blows but the champion, 34, fought fire with fire with powerful upward punches as the pace hardly diminished over the full distance.
The victor barely secured the verdict with scoring tallies of even score, narrow lead and wider gap, but the two athletes were persistent and courageous, exactly what their inspiration the legend stood for.
