British light-heavyweight Buatsi made a winning yet disappointing debut to his career under recent management 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 close 10-round bout at the Co-op Live Arena.
But Parker found success, connecting with powerful single shots in a match where the styles failed to mesh, with frequent clinching marring the fight.
The scoring judges had it 96-94 for to Buatsi, with the third a even score.
"It wasn't my greatest performance but what do champions do? They succeed," Buatsi stated in the arena as he was faced negative reactions from the crowd.
The British fighter bounced back after his initial pro loss - an epic battle with Callum Smith in February - to earn a twentieth professional win.
Several boxing experts thought the challenger, thirty-one, merited the decision but the contender suffered the second loss of his 28-match professional journey.
Buatsi Secures Triumph in Slow Affair
Buatsi's progress has plateaued in recent times through contract problems and extended periods of inactivity.
Previously predicted as the next star of British boxing, he now stands trying to realize his potential - possibly in what seems like a last chance - under new promotional backing.
He opened tentatively, with neither fighter willing to be aggressive in a cagey early stages.
The challenger, whose single earlier setback came at super middleweight against his former opponent in two years ago after breaking his hand in the contest, was making just his second appearance at the higher weight class.
By the middle rounds, the underdog had kept it close, causing problems for Buatsi, who worked behind a solid defense to edge the more effective stanzas.
The audience's tolerance diminished during regular grabbing, with Parker falling to the floor various instances during grappling.
The underdog ended stronger, but multiple periods were difficult to score. Although, ex-champion Carl Frampton - working with the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
The victor progresses, but with the presence of power puncher Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Memorial Fuels Local Rivalry Fight
In the co-main event, Lyndon Arthur overcame Bradley Rea by split-decision in a excellent Manchester vs Manchester battle to secure the European light-heavyweight belt.
The stadium became quiet for a deeply poignant tribute prior to the bout as a bell ceremony rang in memory of Manchester's own Hatton, who passed away 46 years old in last month.
It was the premier televised boxing event in the urban center since Hatton's death. As the last bell disappeared, the silence became a shout of "only one Ricky Hatton".
The action within the ring matched the feeling. Arthur was knocked down by a powerful punch flush on the face in the second round, rising shakily to his footing on the referee's count.
But the traditional red equipment of Arthur soon came forward again. On the opposite side, the opponent - in competitive blue - was injured early, noticeable damage developing under his face as the fighters exchanged powerful shots.
Rea, twenty-seven, landed power punches but the champion, thirty-four, matched the intensity with effective uppercuts as the intensity rarely dropped over twelve rounds.
The victor barely secured the decision with scoring tallies of draw, narrow lead and wider gap, but the two athletes were relentless and courageous, exactly what their hero Hatton represented.
