British light-heavyweight Buatsi earned a win yet disappointing start to his career under new promoters with a points victory over Zach Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a tight 10-round contest at the boxing arena.
But Parker found success, delivering effective individual punches in a contest where the styles failed to mesh, with constant grabbing disrupting the fight.
Two judges judged it 96-94 to Buatsi, with the final judge a 95-95 draw.
"It wasn't my finest display but what do champions do? They prevail," Buatsi commented in the ring as he was greeted with disapproval from the spectators.
The Londoner got back to winning after his maiden career setback - an memorable fight with Callum Smith in last winter - to claim a twentieth professional win.
Some ringside observers thought the challenger, 31, merited the win but the Derbyshire fighter suffered the second loss of his 28-match professional journey.
Buatsi Claims Triumph in Uneventful Affair
Buatsi's progress has plateaued in the past few years through management issues and extended periods of lack of fights.
Earlier forecast as the next star of British boxing, he now finds himself trying to realize his potential - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He began cautiously, with neither fighter ready to take risks in a cagey early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in 2022 after suffering a hand injury in the contest, was competing in only his second bout at light-heavyweight.
By the fight's midpoint, the underdog had kept it close, causing problems for the favorite, who operated with a solid defense to barely take the more effective stanzas.
The crowd's patience decreased during constant clinching, with Parker slipping to the canvas various instances during clinches.
The underdog finished the stronger, but several stanzas were challenging to assess. However, ex-champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just only one stanza.
The victor advances, but with the presence of power puncher Benavidez, and Russian star Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Tribute Fuels Local Rivalry Battle
In the secondary fight, Lyndon Arthur beat Bradley Rea by divided decision in a outstanding local rivalry contest to win the European light heavyweight championship.
The venue became quiet for a extremely emotional tribute ahead of the contest as 10 bells sounded in memory of the city's native Ricky Hatton, who died aged 46 in recently.
It was the first major televised boxing event in the city since the passing of Hatton. As the last bell ended, the silence gave way to a shout of "there's just one Ricky Hatton".
The competition within the ring reflected the sentiment. Arthur was knocked down by a left hook directly to the jaw in the second round, rising shakily to his position on the eight count.
But the red-colored shorts of Arthur soon advanced again. On the opposite side, the opponent - in competitive blue - was damaged early, noticeable damage appearing under his orbital area as the fighters landed punishing blows.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the action hardly diminished over 12 rounds.
The victor barely secured the result with scoring tallies of 114-114, close margin and wider gap, but the two athletes were determined and brave, everything their idol Hatton embodied.
