British light heavyweight Buatsi earned a win yet underwhelming beginning to life under new promoters with a decision win over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a split decision in a close 10-round contest at the boxing arena.
But the challenger had his moments, delivering effective clean blows in a fight where the approaches failed to mesh, with frequent clinching disrupting the contest.
Two judges scored it 96-94 to Buatsi, with the remaining official a 95-95.
"It wasn't my finest showing but what do champions do? They prevail," Buatsi said in the ring as he was greeted with boos from the audience.
The Londoner bounced back after his initial pro loss - an memorable fight with Callum Smith in last winter - to secure a 20th pro success.
Several boxing experts felt the challenger, 31, should have been awarded the decision but the British boxer experienced the second setback of his 28-bout career.
Buatsi Claims Victory in Dull Affair
Buatsi's progress has slowed in recent years through management issues and extended periods of inactivity.
Earlier forecast as the rising talent of British boxing, he now stands trying to achieve expectations - maybe in what feels like a ultimate opportunity - under fresh management.
He began cautiously, with both competitors ready to be aggressive in a calculated opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against John Ryder in 2022 after suffering a hand injury mid-fight, was participating in his second appearance at light-heavyweight.
By the fight's midpoint, Parker had stayed in contention, making life awkward for the favorite, who utilized a solid defense to narrowly win the better rounds.
The spectators' acceptance wore thin during constant clinching, with the challenger slipping to the canvas various instances during grappling.
The underdog ended stronger, but several stanzas were difficult to score. However, ex-champion Carl Frampton - providing analysis for Dazn - had it significantly in favor for the challenger, awarding Buatsi just a single round.
The victor progresses, but with the likes of power puncher Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - based on this performance - still seems difficult.
Ricky Hatton Homage Motivates Local Rivalry Battle
In the secondary fight, Lyndon Arthur defeated Rea by split-decision in a terrific all-Manchester fight to win the European light heavyweight title.
The stadium fell silent for a deeply poignant homage before the fight as ten bells sounded in remembrance of Manchester's own Ricky Hatton, who passed away aged 46 in September.
It was the initial significant broadcast boxing event in the urban center since the passing of Hatton. As the last bell faded, the quiet transitioned to a chant of "there's only one Hatton".
The competition within the ring reflected the emotion. Arthur was floored by a significant blow flush on the chin in the second round, standing uncertainly to his feet on the eight count.
But the Manchester United-red attire of Arthur soon advanced again. From the other corner, Rea - in competitive blue - was injured early, heavy swelling forming under his eye as the duo exchanged powerful shots.
Rea, twenty-seven, delivered effective strikes but the champion, 34, matched the intensity with effective uppercuts as the pace seldom decreased over twelve rounds.
The victor narrowly won the verdict with official scores of draw, narrow lead and 115-112, but both fighters were determined and brave, all the qualities their idol the legend stood for.
