British light-heavyweight Buatsi earned a win yet disappointing debut to his career under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a close ten-round fight at the Manchester venue.
But Parker had his moments, landing some telling single shots in a contest where the approaches failed to mesh, with constant grabbing spoiling the fight.
Two judges judged it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my greatest display but what do champions do? They prevail," Buatsi stated in the ring as he was faced boos from the audience.
The British fighter returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in February - to claim a 20th pro success.
Some ringside observers felt the challenger, thirty-one, should have been awarded the victory but the British boxer endured the second defeat of his 28-fight career.
The Champion Earns Win in Dull Encounter
The fighter's advancement has stalled in recent times through contract problems and considerable time of lack of fights.
Once tipped as the rising talent of British boxing, he now finds himself trying to realize his potential - maybe in what appears to be a ultimate opportunity - under new promotional backing.
He opened tentatively, with both competitors prepared to overcommit in a tentative early stages.
The challenger, whose only previous defeat came at super middleweight against John Ryder in 2022 after damaging his hand in the contest, was making just his second appearance at light heavyweight.
By the halfway stage, Parker had stayed in contention, causing problems for the favorite, who worked behind a protective stance to narrowly win the cleaner stanzas.
The audience's tolerance diminished because of constant clinching, with Parker falling to the floor several times during close exchanges.
The underdog ended stronger, but many rounds were hard to judge. However, former world champion the boxing analyst - working with Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
The victor moves on, but with the presence of power puncher Benavidez, and Russian star Dmitry Bivol leading the category, the journey to titles - based on this performance - still appears challenging.
Ricky Hatton Homage Fuels All-Manchester Battle
In the secondary fight, Arthur beat Rea by close verdict in a terrific local rivalry fight to capture the European light heavyweight title.
The arena grew hushed for a extremely emotional memorial ahead of the contest as 10 bells rang in honor of local hero Ricky Hatton, who died aged 46 in September.
It was the premier televised boxing event in the city since Hatton's passing. As the concluding sound disappeared, the silence gave way to a chant of "only one Ricky Hatton".
The fighting inside the ropes equaled the emotion. The eventual winner was sent to the canvas by a left hook flush on the jaw in the early round, rising shakily to his footing on the count of eight.
But the red-colored attire of the fighter soon pressed ahead again. Across the ring, Rea - in competitive blue - was damaged early, heavy swelling forming under his eye as the pair landed punishing blows.
The challenger, twenty-seven, landed power punches but the champion, thirty-four, matched the intensity with stinging uppercuts as the intensity hardly diminished over 12 rounds.
Arthur narrowly won the decision with judges scorecards of even score, narrow lead and wider gap, but both fighters were determined and full of heart, exactly what their hero the legend stood for.
