British light-heavyweight Buatsi made a winning yet disappointing start to life under fresh promotional backing with a decision win over Zach Parker in the Manchester arena.
The Olympic bronze medallist's work rate appeared to earn him a majority decision in a close ten-round contest at the boxing arena.
But the challenger landed significant shots, landing some telling clean blows in a contest where the techniques didn't complement each other, with frequent clinching disrupting the contest.
The officials had it 96-94 to Buatsi, with the third a even score.
"It wasn't my best display but what defines champions? They prevail," the victor said in the ring as he was met by negative reactions from the crowd.
The British fighter bounced back after his initial pro loss - an thrilling contest with his previous opponent in February - to secure a 20th career victory.
Some ringside observers believed the challenger, thirty-one, merited the win but the contender endured the second loss of his 28-bout professional journey.
The Champion Secures Win in Slow Match
His career development has plateaued in recent years through management issues and extended periods of lack of fights.
Previously predicted as the next star of UK boxing, he now finds himself trying to realize his potential - maybe in what feels like a last chance - under recent support.
He opened tentatively, with neither fighter willing to overcommit in a cagey early stages.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after damaging his hand in the contest, was competing in only his second fight at light-heavyweight.
By the fight's midpoint, the underdog had kept it close, making life awkward for the favorite, who utilized a solid defense to narrowly win the more effective periods.
The crowd's patience wore thin during frequent holding, with Parker falling to the floor various instances during clinches.
The underdog closed well, but several stanzas were hard to judge. Nevertheless, former world champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just one round.
Buatsi moves on, but with the caliber of hard hitter David Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the journey to titles - based on this performance - still looks steep.
Hatton Homage Inspires Manchester Derby Fight
In the secondary fight, Arthur overcame Rea by split-decision in a terrific local rivalry fight to win the European light-heavyweight championship.
The stadium fell silent for a deeply poignant memorial ahead of the contest as a bell ceremony tolled in remembrance of local hero Ricky Hatton, who succumbed aged 46 in recently.
It was the premier televised fight night in the urban center since Hatton's passing. As the concluding sound faded, the quiet became a roar of "there's only one Hatton".
The competition inside the ropes equaled the feeling. Arthur was sent to the canvas by a powerful punch flush on the jaw in the second round, standing uncertainly to his footing on the eight count.
But the Manchester United-red shorts of Arthur soon advanced again. Across the ring, Rea - in opposing blue - was injured early, heavy swelling appearing under his orbital area as the duo landed powerful shots.
The challenger, twenty-seven, delivered effective strikes but the champion, 34, matched the intensity with stinging uppercuts as the action rarely dropped over 12 rounds.
Arthur narrowly won the decision with official scores of 114-114, close margin and clearer margin, but the two athletes were relentless and courageous, all the qualities their idol the legend stood for.
