British light heavyweight Buatsi earned a win yet underwhelming beginning to life under recent management with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a tight 10-round fight at the Co-op Live Arena.
But Parker found success, connecting with powerful clean blows in a match where the styles failed to mesh, with excessive holding spoiling the fight.
The scoring judges scored it 96-94 in favor to Buatsi, with the third a 95-95 draw.
"It wasn't my finest display but what do champions do? They prevail," Buatsi stated in the arena as he was met by disapproval from the crowd.
The British fighter returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in February - to secure a twentieth professional win.
Several boxing experts thought the challenger, thirty-one, should have been awarded the win but the British boxer endured the second defeat of his 28-match career.
The Champion Earns Victory in Uneventful Affair
The fighter's advancement has slowed in recent times through management issues and considerable time of inactivity.
Earlier forecast as the future of UK boxing, he now is positioned trying to fulfil that early promise - perhaps in what appears to be a ultimate opportunity - under fresh management.
He began cautiously, with both competitors prepared to take risks in a tentative initial rounds.
The challenger, whose sole prior loss came at the lower weight class against John Ryder in 2022 after suffering a hand injury mid-fight, was participating in his second fight at light heavyweight.
By the middle rounds, Parker had made it competitive, making life awkward for the favorite, who worked behind a solid defense to barely take the better stanzas.
The spectators' acceptance wore thin amid constant clinching, with the challenger falling to the floor multiple occasions during close exchanges.
The underdog closed well, but many rounds were difficult to score. Although, former world champion Carl Frampton - providing analysis for the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
Buatsi advances, but with the presence of power puncher David Benavidez, and Eastern European fighter Bivol leading the category, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Memorial Inspires Manchester Derby Contest
In the co-main event, Lyndon Arthur overcame Rea by close verdict in a terrific Manchester vs Manchester battle to win the European light heavyweight title.
The stadium grew hushed for a profoundly moving tribute ahead of the contest as 10 bells tolled in honor of Manchester's own Hatton, who succumbed at age 46 in recently.
It was the first major televised fight night in the urban center since the passing of Hatton. As the final chime disappeared, the quiet gave way to a roar of "only one Hatton".
The action within the ring equaled the feeling. Arthur was sent to the canvas by a powerful punch squarely on the jaw in the initial stage, rising shakily to his footing on the eight count.
But the red-colored attire of Arthur soon pressed ahead again. Across the ring, Rea - in competitive blue - was marked up soon, heavy swelling developing under his face as the duo traded punishing blows.
Rea, 27, landed power punches but Arthur, thirty-four, matched the intensity with powerful upward punches as the action hardly diminished over 12 rounds.
Arthur barely secured the result with judges scorecards of even score, narrow lead and wider gap, but each competitor were relentless and brave, everything their hero the legend represented.
