British light-heavyweight Buatsi earned a win yet disappointing debut to his career under fresh promotional backing with a points victory over Zach Parker in Manchester.
The Olympic bronze medallist's punch output likely gained him a majority decision in a tight ten-round bout at the Co-op Live Arena.
But the challenger had his moments, delivering effective individual punches in a fight where the styles didn't complement each other, with frequent clinching spoiling the action.
The scoring judges scored it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my best performance but what defines champions? They prevail," the victor commented in the arena as he was greeted with boos from the audience.
The Londoner bounced back after his maiden career setback - an memorable fight with his previous opponent in last winter - to claim a twentieth professional win.
Various analysts felt the challenger, 31, deserved the decision but the contender experienced the second setback of his 28-fight professional journey.
The Champion Secures Win in Slow Affair
Buatsi's progress has slowed in the past few years through management issues and extended periods of lack of fights.
Earlier forecast as the future of UK boxing, he now stands trying to fulfil that early promise - maybe in what feels like a final roll of the dice - under recent support.
He opened tentatively, with the two boxers ready to overcommit in a tentative initial rounds.
Parker, whose only previous defeat came at super middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was competing in only his second fight at the higher weight class.
By the middle rounds, the underdog had made it competitive, creating difficulties for the favorite, who utilized a solid defense to barely take the more effective rounds.
The crowd's patience wore thin during frequent holding, with Parker slipping to the canvas several times during grappling.
Parker finished the stronger, but several stanzas were difficult to score. Nevertheless, former world champion Carl Frampton - commentating on the broadcast network - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
The victor moves on, but with the caliber of hard hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Homage Fuels Manchester Derby Contest
In the supporting bout, Arthur beat Bradley Rea by close verdict in a outstanding local rivalry contest to secure the continental belt.
The stadium fell silent for a deeply poignant tribute prior to the bout as 10 bells sounded in memory of Manchester's own Hatton, who succumbed at age 46 in recently.
It was the first major televised fight night in the urban center since Hatton's death. As the final chime disappeared, the quiet gave way to a roar of "only one Hatton".
The fighting during the bout equaled the feeling. Arthur was floored by a powerful punch flush on the chin in the initial stage, standing uncertainly to his footing on the referee's count.
But the Manchester United-red attire of Arthur soon pressed ahead again. Across the ring, the opponent - in opposing blue - was damaged soon, heavy swelling developing under his eye as the pair landed hard punches.
Rea, twenty-seven, connected with strong blows but Arthur, 34, matched the intensity with effective uppercuts as the intensity seldom decreased over the full distance.
Arthur barely secured the decision with official scores of 114-114, narrow lead and wider gap, but both fighters were determined and full of heart, everything their hero Hatton embodied.
