British light-heavyweight Buatsi made a winning yet underwhelming start to life under fresh promotional backing with a decision win over Zach Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a split decision in a competitive 10-round contest at the Manchester venue.
But the challenger had his moments, delivering effective single shots in a match where the approaches failed to mesh, with excessive holding marring the fight.
The scoring judges had it 96-94 for to the winner, with the third a even score.
"It wasn't my greatest display but what do champions do? They win," Buatsi stated in the ringside as he was faced disapproval from the audience.
The Londoner bounced back after his maiden career setback - an epic battle with Callum Smith in last winter - to earn a 20th pro success.
Various analysts believed the challenger, thirty-one, deserved the victory but the British boxer endured the second loss of his 28-fight career.
Buatsi Claims Win in Dull Affair
Buatsi's progress has stalled in the past few years through contract problems and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now finds himself trying to achieve expectations - maybe in what seems like a final roll of the dice - under recent support.
He opened tentatively, with neither fighter prepared to overcommit in a cagey initial rounds.
Parker, whose sole prior loss came at the lower weight class against John Ryder in two years ago after suffering a hand injury in the contest, was competing in only his second fight at the higher weight class.
By the halfway stage, the underdog had kept it close, making life awkward for Buatsi, who utilized a protective stance to edge the more effective rounds.
The spectators' acceptance decreased amid regular grabbing, with Parker going down multiple occasions during close exchanges.
The underdog finished the stronger, but many rounds were hard to judge. Nevertheless, previous titleholder Carl Frampton - commentating on the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just a single round.
The victor moves on, but with the caliber of heavy hitter Benavidez, and Russian champion Bivol leading the category, the road to world glory - judging by this showing - still looks steep.
Hatton Homage Inspires Manchester Derby Battle
In the co-main event, Arthur defeated Bradley Rea by close verdict in a outstanding local rivalry contest to secure the European light heavyweight championship.
The venue fell silent for a extremely emotional tribute ahead of the contest as 10 bells sounded in memory of the city's native Hatton, who succumbed 46 years old in recently.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the final chime ended, the silence transitioned to a shout of "only one Ricky Hatton".
The fighting within the ring reflected the emotion. Arthur was floored by a significant blow flush on the chin in the initial stage, getting up unsteadily to his footing on the eight count.
But the Manchester United-red shorts of Arthur soon came forward again. Across the ring, the opponent - in opposing blue - was damaged early, noticeable damage developing under his orbital area as the pair traded punishing blows.
The challenger, 27, connected with strong blows but the champion, 34, matched the intensity with stinging uppercuts as the intensity seldom decreased over 12 rounds.
Arthur barely secured the result with judges scorecards of even score, close margin and 115-112, but both fighters were determined and courageous, all the qualities their hero Hatton represented.
