British light-heavyweight Buatsi made a winning yet disappointing beginning to his career under recent management with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level likely gained him a majority decision in a close 10-round contest at the Co-op Live Arena.
But Parker landed significant shots, landing some telling individual punches in a match where the styles failed to mesh, with constant grabbing marring the contest.
The officials judged it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my finest showing but what defines champions? They prevail," Buatsi commented in the arena as he was met by boos from the crowd.
The British fighter returned to winning ways after his initial pro loss - an memorable fight with his previous opponent in February - to earn a 20th pro success.
Various analysts believed the challenger, 31, merited the victory but the contender suffered the second setback of his 28-fight career.
Buatsi Earns Win in Uneventful Affair
His career development has slowed in recent times through contract problems and considerable time of lack of fights.
Once tipped as the rising talent of UK boxing, he now stands trying to fulfil that early promise - maybe in what appears to be a final roll of the dice - under fresh management.
He began cautiously, with neither fighter prepared to overcommit in a calculated opening few rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after breaking his hand mid-fight, was competing in only his second appearance at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, creating difficulties for the favorite, who operated with a protective stance to narrowly win the more effective periods.
The audience's tolerance diminished amid frequent holding, with Parker falling to the floor several times during grappling.
The underdog finished the stronger, but multiple periods were difficult to score. However, previous titleholder the boxing analyst - working with Dazn - had it strongly leaning for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the presence of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Memorial Motivates All-Manchester Fight
In the secondary fight, Arthur defeated Rea by split-decision in a outstanding Manchester vs Manchester fight to win the continental belt.
The arena fell silent for a extremely emotional memorial ahead of the contest as 10 bells tolled in memory of local hero Ricky Hatton, who succumbed at age 46 in September.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the concluding sound disappeared, the quiet transitioned to a shout of "there's just one Hatton".
The competition within the ring reflected the emotion. The eventual winner was sent to the canvas by a powerful punch squarely on the face in the initial stage, rising shakily to his feet on the eight count.
But the red-colored shorts of the fighter soon advanced again. Across the ring, Rea - in rival City blue - was damaged quickly, heavy swelling forming under his eye as the fighters landed punishing blows.
Rea, 27, landed power punches but the champion, thirty-four, fought fire with fire with powerful upward punches as the pace hardly diminished over 12 rounds.
The victor barely secured the decision with scoring tallies of even score, 115-113 and wider gap, but both fighters were relentless and brave, exactly what their inspiration Hatton represented.
