British light-heavyweight Buatsi earned a win yet disappointing start to his career under recent management with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's punch output seemingly secured him a majority decision in a close ten-round fight at the boxing arena.
But Parker landed significant shots, delivering effective clean blows in a match where the techniques didn't complement each other, with frequent clinching spoiling the contest.
The officials judged it 96-94 for to the winner, with the final judge a 95-95.
"It wasn't my greatest showing but what do champions do? They prevail," Buatsi commented in the ringside as he was greeted with negative reactions from the audience.
The Londoner got back to winning after his initial pro loss - an epic battle with his previous opponent in last winter - to claim a 20th career victory.
Several boxing experts thought Parker, 31, should have been awarded the victory but the British boxer endured the second setback of his 28-match professional journey.
The Champion Earns Win in Dull Match
Buatsi's progress has slowed in the past few years through contract problems and long spells of lack of fights.
Previously predicted as the next star of British boxing, he now finds himself trying to achieve expectations - possibly in what appears to be a final roll of the dice - under recent support.
He started carefully, with neither fighter ready to take risks in a calculated early stages.
Parker, whose only previous defeat came at super middleweight against his former opponent in two years ago after breaking his hand in the contest, was making just his second bout at the higher weight class.
By the fight's midpoint, the underdog had made it competitive, creating difficulties for the favorite, who utilized a tight guard to barely take the better rounds.
The crowd's patience decreased amid regular grabbing, with the challenger slipping to the canvas multiple occasions during grappling.
Parker finished the stronger, but multiple periods were difficult to score. However, ex-champion Carl Frampton - working with Dazn - had it significantly in favor for the challenger, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of hard hitter Benavidez, and Russian star Dmitry Bivol ruling the division, the road to world glory - on this evidence - still seems difficult.
Ricky Hatton Homage Fuels Local Rivalry Contest
In the co-main event, Lyndon Arthur defeated Bradley Rea by split-decision in a excellent Manchester vs Manchester contest to secure the European light-heavyweight belt.
The stadium fell silent for a deeply poignant memorial ahead of the contest as ten bells sounded in memory of Manchester's own Hatton, who died at age 46 in September.
It was the first major televised match card in the location since the passing of Hatton. As the last bell disappeared, the quiet became a shout of "there's just one Hatton".
The action within the ring equaled the feeling. Arthur was floored by a left hook directly to the face in the second round, standing uncertainly to his footing on the referee's count.
But the traditional red attire of the fighter soon advanced again. From the other corner, Rea - in competitive blue - was damaged early, noticeable damage developing under his face as the pair landed punishing blows.
Rea, 27, connected with strong blows but Arthur, thirty-four, responded in kind with stinging uppercuts as the action rarely dropped over twelve rounds.
Arthur narrowly won the decision with judges scorecards of draw, close margin and clearer margin, but each competitor were determined and courageous, exactly what their hero the legend stood for.
