British light heavyweight Buatsi earned a win yet underwhelming start to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic medal winner's work rate appeared to earn him a judges' verdict in a competitive ten-round fight at the Co-op Live Arena.
But Parker landed significant shots, landing some telling single shots in a match where the approaches failed to mesh, with excessive holding marring the action.
Two judges judged it 96-94 for to the winner, with the final judge a even score.
"It wasn't my best showing but what do champions do? They succeed," Buatsi said in the ringside as he was faced disapproval from the spectators.
The British fighter returned to winning ways after his maiden career setback - an memorable fight with his previous opponent in last winter - to claim a twentieth professional win.
Several boxing experts believed Parker, 31, merited the decision but the British boxer endured the second defeat of his 28-bout career.
The Champion Claims Victory in Uneventful Affair
His career development has slowed in recent times through contract problems and considerable time of inactivity.
Once tipped as the next star of British boxing, he now is positioned trying to achieve expectations - possibly in what feels like a last chance - under new promotional backing.
He opened tentatively, with both competitors ready to take risks in a calculated opening few rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in two years ago after breaking his hand in the contest, was making just his second fight at light-heavyweight.
By the halfway stage, the underdog had stayed in contention, causing problems for the favorite, who operated with a protective stance to edge the cleaner stanzas.
The spectators' acceptance wore thin because of constant clinching, with Parker slipping to the canvas various instances during clinches.
Parker finished the stronger, but many rounds were difficult to score. Although, former world champion Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for Parker, awarding Buatsi just a single round.
Buatsi progresses, but with the presence of power puncher Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Tribute Fuels Local Rivalry Fight
In the supporting bout, Arthur beat Bradley Rea by divided decision in a terrific local rivalry contest to capture the European light-heavyweight championship.
The venue became quiet for a profoundly moving homage prior to the bout as ten bells tolled in remembrance of Manchester's own Hatton, who died 46 years old in last month.
It was the premier televised match card in the urban center since Hatton's death. As the concluding sound disappeared, the stillness transitioned to a shout of "only one Hatton".
The competition inside the ropes reflected the sentiment. The eventual winner was sent to the canvas by a powerful punch flush on the jaw in the second round, getting up unsteadily to his footing on the referee's count.
But the Manchester United-red equipment of Arthur soon advanced again. On the opposite side, Rea - in opposing blue - was injured soon, noticeable damage forming under his orbital area as the fighters landed powerful shots.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, responded in kind with effective uppercuts as the intensity rarely dropped over twelve rounds.
The victor edged the decision with judges scorecards of draw, narrow lead and wider gap, but the two athletes were determined and full of heart, all the qualities their hero the legend represented.
