British light heavyweight Buatsi earned a win yet unimpressive beginning to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic medal winner's work rate likely gained him a judges' verdict in a tight ten-round fight at the boxing arena.
But the challenger landed significant shots, landing some telling single shots in a fight where the styles failed to mesh, with constant grabbing marring the action.
The scoring judges had it 96-94 in favor to Buatsi, with the remaining official a 95-95.
"It wasn't my finest showing but how do champions respond? They succeed," Buatsi commented in the ring as he was greeted with boos from the audience.
The British fighter bounced back after his first professional defeat - an memorable fight with Callum Smith in last winter - to secure a 20th pro success.
Various analysts thought the challenger, thirty-one, should have been awarded the victory but the contender endured the second setback of his 28-fight professional journey.
The Champion Earns Triumph in Dull Match
The fighter's advancement has slowed in recent years through contract problems and long spells of lack of fights.
Once tipped as the next star of the British fight scene, he now is positioned trying to realize his potential - possibly in what appears to be a final roll of the dice - under fresh management.
He started carefully, with the two boxers prepared to take risks in a calculated initial rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was competing in only his second bout at light heavyweight.
By the halfway stage, the underdog had made it competitive, making life awkward for Buatsi, who worked behind a tight guard to narrowly win the cleaner periods.
The audience's tolerance wore thin amid constant clinching, with Parker slipping to the canvas several times during clinches.
The underdog ended stronger, but many rounds were difficult to score. Although, ex-champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, scoring for Buatsi just one round.
The victor advances, but with the presence of power puncher Benavidez, and Russian star Bivol leading the category, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Tribute Inspires Manchester Derby Fight
In the secondary fight, Arthur beat Rea by close verdict in a outstanding all-Manchester fight to capture the European light heavyweight title.
The venue became quiet for a profoundly moving homage prior to the bout as a bell ceremony sounded in memory of Manchester's own Hatton, who passed away aged 46 in recently.
It was the initial significant broadcast fight night in the city since Hatton's passing. As the concluding sound ended, the quiet transitioned to a chant of "only one Hatton".
The action inside the ropes matched the sentiment. Arthur was floored by a significant blow directly to the chin in the initial stage, standing uncertainly to his feet on the eight count.
But the Manchester United-red shorts of the fighter soon pressed ahead again. From the other corner, the opponent - in competitive blue - was injured soon, significant bruising appearing under his eye as the fighters landed hard punches.
The challenger, 27, delivered effective strikes but the champion, 34, matched the intensity with powerful upward punches as the pace rarely dropped over the full distance.
Arthur edged the result with official scores of 114-114, narrow lead and 115-112, but the two athletes were determined and brave, everything their inspiration Hatton represented.
