UK light-heavyweight Buatsi earned a win yet disappointing beginning to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a judges' verdict in a competitive ten-round fight at the boxing arena.
But the challenger landed significant shots, connecting with powerful individual punches in a contest where the approaches didn't complement each other, with frequent clinching disrupting the contest.
The officials judged it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my finest showing but what defines champions? They win," Buatsi said in the ring as he was greeted with boos from the crowd.
The British fighter returned to winning ways after his maiden career setback - an memorable fight with Callum Smith in last winter - to claim a 20th career victory.
Some ringside observers felt the challenger, thirty-one, merited the decision but the British boxer suffered the second loss of his 28-match career.
Buatsi Earns Victory in Slow Encounter
Buatsi's progress has plateaued in the past few years through contract problems and extended periods of inactivity.
Earlier forecast as the future of British boxing, he now is positioned trying to realize his potential - maybe in what appears to be a last chance - under new promotional backing.
He started carefully, with the two boxers ready to overcommit in a tentative initial rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand during the bout, was competing in only his second appearance at light-heavyweight.
By the middle rounds, the underdog had made it competitive, causing problems for Buatsi, who worked behind a protective stance to narrowly win the more effective rounds.
The crowd's patience diminished during constant clinching, with Parker going down various instances during grappling.
Parker closed well, but many rounds were challenging to assess. Although, ex-champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just one round.
Buatsi progresses, but with the presence of power puncher Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - judging by this showing - still appears challenging.
Hatton Homage Fuels All-Manchester Fight
In the secondary fight, Arthur defeated Rea by close verdict in a excellent all-Manchester contest to capture the continental belt.
The venue grew hushed for a profoundly moving memorial ahead of the contest as ten bells rang in memory of local hero Hatton, who succumbed 46 years old in recently.
It was the first major televised boxing event in the city since the passing of Hatton. As the final chime disappeared, the silence transitioned to a shout of "there's only one Ricky Hatton".
The action within the ring equaled the sentiment. Arthur was sent to the canvas by a significant blow squarely on the jaw in the initial stage, standing uncertainly to his feet on the referee's count.
But the traditional red shorts of the fighter soon advanced again. From the other corner, Rea - in rival City blue - was marked up quickly, significant bruising developing under his orbital area as the pair exchanged hard punches.
Rea, twenty-seven, connected with strong blows but Arthur, thirty-four, responded in kind with stinging uppercuts as the pace seldom decreased over the full distance.
Arthur edged the decision with judges scorecards of even score, narrow lead and wider gap, but the two athletes were relentless and full of heart, everything their hero Hatton stood for.
