British 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 work rate likely gained him a majority decision in a close ten-round fight at the Manchester venue.
But Parker landed significant shots, connecting with powerful single shots in a match where the techniques failed to mesh, with constant grabbing spoiling the fight.
The scoring judges scored it 96-94 in favor to the winner, with the third a even score.
"It wasn't my best display but how do champions respond? They win," the victor stated in the ringside as he was faced disapproval from the crowd.
The Londoner bounced back after his maiden career setback - an epic battle with Callum Smith in February - to secure a 20th career victory.
Some ringside observers thought Parker, 31, deserved the decision but the Derbyshire fighter experienced the second loss of his 28-match career.
Buatsi Secures Victory in Dull Match
His career development has stalled in recent years through promotional disputes and considerable time of inactivity.
Earlier forecast as the next star of the British fight scene, he now is positioned trying to achieve expectations - perhaps in what appears to be a last chance - under fresh management.
He opened tentatively, with both competitors willing to take risks in a tentative opening few rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after damaging his hand in the contest, was competing in only his second fight at light-heavyweight.
By the middle rounds, Parker had made it competitive, making life awkward for the favorite, who worked behind a solid defense to barely take the better rounds.
The audience's tolerance diminished during regular grabbing, with the challenger slipping to the canvas several times during close exchanges.
The underdog closed well, but several stanzas were difficult to score. However, previous titleholder Carl Frampton - working with the broadcast network - had it strongly leaning for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the caliber of hard hitter Benavidez, and Eastern European fighter Bivol ruling the division, the road to world glory - judging by this showing - still appears challenging.
Hatton Memorial Motivates Manchester Derby Fight
In the supporting bout, Lyndon Arthur defeated Rea by close verdict in a outstanding Manchester vs Manchester fight to capture the continental title.
The venue became quiet for a extremely emotional memorial prior to the bout as ten bells tolled in honor of Manchester's own Hatton, who succumbed aged 46 in last month.
It was the first major televised boxing event in the urban center since Hatton's death. As the concluding sound faded, the stillness gave way to a roar of "only one Hatton".
The fighting inside the ropes matched the feeling. The eventual winner was knocked down by a powerful punch directly to the face in the early round, getting up unsteadily to his position on the referee's count.
But the traditional red shorts of Arthur soon pressed ahead again. From the other corner, the opponent - in competitive blue - was injured quickly, noticeable damage forming under his eye as the fighters exchanged hard punches.
Rea, 27, landed power punches but the champion, thirty-four, responded in kind with effective uppercuts as the intensity seldom decreased over the full distance.
The victor barely secured the verdict with official scores of 114-114, close margin and wider gap, but each competitor were persistent and brave, exactly what their hero Hatton represented.
