British light-heavyweight Buatsi secured a victory 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 work rate likely gained him a split decision in a tight ten-round contest at the Manchester venue.
But Parker found success, connecting with powerful clean blows in a fight where the approaches failed to mesh, with excessive holding spoiling the action.
Two judges scored it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my greatest display but what do champions do? They succeed," the victor commented in the ring as he was greeted with boos from the spectators.
The Londoner got back to winning after his first professional defeat - an epic battle with Callum Smith in last winter - to earn a twentieth professional win.
Some ringside observers felt the challenger, 31, deserved the decision but the contender suffered the second loss of his 28-match professional journey.
Buatsi Secures Victory in Slow Encounter
Buatsi's progress has stalled in the past few years through promotional disputes and extended periods of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now is positioned trying to realize his potential - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with both competitors willing to take risks in a tentative initial rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in 2022 after suffering a hand injury in the contest, was participating in his second fight at light heavyweight.
By the middle rounds, the underdog had kept it close, causing problems for Buatsi, who operated with a tight guard to edge the more effective periods.
The crowd's patience decreased amid constant clinching, with Parker falling to the floor several times during grappling.
Parker closed well, but several stanzas were hard to judge. Nevertheless, ex-champion the boxing analyst - working with the broadcast network - had it significantly in favor for Parker, awarding Buatsi just only one stanza.
Buatsi progresses, but with the likes of heavy hitter David Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - based on this performance - still appears challenging.
Ricky Hatton Homage Motivates Manchester Derby Contest
In the supporting bout, Arthur overcame Rea by split-decision in a excellent local rivalry contest to capture the European light heavyweight title.
The venue became quiet for a profoundly moving homage ahead of the contest as 10 bells rang in memory of Manchester's own Ricky Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast boxing event in the city since the passing of Hatton. As the concluding sound faded, the stillness transitioned to a roar of "there's just one Ricky Hatton".
The action during the bout equaled the feeling. The eventual winner was floored by a left hook flush on the face in the early round, rising shakily to his feet on the referee's count.
But the Manchester United-red attire of Arthur soon came forward again. From the other corner, Rea - in rival City blue - was marked up early, noticeable damage forming under his eye as the fighters exchanged powerful shots.
Rea, twenty-seven, connected with strong blows but the champion, thirty-four, fought fire with fire with stinging uppercuts as the action rarely dropped over twelve rounds.
The victor barely secured the result with official scores of 114-114, narrow lead and clearer margin, but each competitor were persistent and full of heart, all the qualities their hero Hatton stood for.
