British light heavyweight Buatsi earned a win yet underwhelming debut to life under recent management with a unanimous decision over Zach Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a majority decision in a close ten-round fight at the Manchester venue.
But Parker found success, landing some telling clean blows in a contest where the techniques failed to mesh, with frequent clinching spoiling the action.
Two judges scored it 96-94 to the winner, with the remaining official a even score.
"It wasn't my greatest display but what do champions do? They prevail," the victor said in the ringside as he was met by disapproval from the spectators.
The Londoner returned to winning ways after his initial pro loss - an thrilling contest with Callum Smith in February - to earn a twentieth professional win.
Some ringside observers felt Parker, 31, deserved the win but the contender experienced the second loss of his 28-match career.
The Champion Claims Win in Uneventful Affair
The fighter's advancement has plateaued in recent times through management issues and considerable time of inactivity.
Previously predicted as the next star of UK boxing, he now is positioned trying to fulfil that early promise - possibly in what seems like a last chance - under new promotional backing.
He started carefully, with both competitors prepared to be aggressive in a cagey initial rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in 2022 after damaging his hand in the contest, was participating in his second appearance at the higher weight class.
By the halfway stage, the underdog had made it competitive, causing problems for the favorite, who utilized a solid defense to narrowly win the more effective rounds.
The audience's tolerance decreased amid regular grabbing, with the challenger slipping to the canvas various instances during clinches.
Parker closed well, but many rounds were difficult to score. Nevertheless, ex-champion Carl Frampton - working with the broadcast network - had it particularly wide for Parker, scoring for Buatsi just a single round.
Buatsi advances, but with the likes of heavy hitter Benavidez, and Russian champion Bivol leading the category, the path to championship success - judging by this showing - still seems difficult.
Ricky Hatton Tribute Fuels All-Manchester Contest
In the supporting bout, Arthur overcame Rea by split-decision in a terrific all-Manchester battle to secure the European light heavyweight belt.
The arena became quiet for a deeply poignant memorial prior to the bout as a bell ceremony tolled in honor of the city's native Ricky Hatton, who succumbed 46 years old in last month.
It was the first major televised fight night in the location since the passing of Hatton. As the final chime ended, the stillness became a chant of "only one Hatton".
The action during the bout matched the emotion. The eventual winner was sent to the canvas by a significant blow flush on the jaw in the early round, standing uncertainly to his footing on the count of eight.
But the traditional red attire of Arthur soon came forward again. On the opposite side, Rea - in opposing blue - was damaged early, heavy swelling developing under his face as the pair exchanged powerful shots.
The challenger, twenty-seven, connected with strong blows but the champion, 34, matched the intensity with effective uppercuts as the action hardly diminished over the full distance.
The victor narrowly won the decision with scoring tallies of even score, 115-113 and 115-112, but both fighters were determined and full of heart, exactly what their hero the legend embodied.
