British light heavyweight Buatsi earned a win yet underwhelming debut to his career under new promoters with a decision win over Zach Parker in Manchester.
The Olympic medal winner's activity level seemingly secured him a majority decision in a competitive ten-round contest at the Manchester venue.
But Parker had his moments, delivering effective single shots in a fight where the approaches didn't complement each other, with excessive holding disrupting the action.
The scoring judges judged it 96-94 to the winner, with the final judge a even score.
"It wasn't my finest showing but what defines champions? They win," the victor said in the ring as he was faced boos from the crowd.
The Londoner got back to winning after his initial pro loss - an thrilling contest with his previous opponent in last winter - to secure a 20th career victory.
Some ringside observers thought Parker, 31, should have been awarded the victory but the contender endured the second setback of his 28-fight career.
The Champion Earns Win in Dull Encounter
His career development has slowed in the past few years through contract problems and long spells of inactivity.
Once tipped as the next star of the British fight scene, he now finds himself trying to realize his potential - maybe in what appears to be a last chance - under recent support.
He opened tentatively, with neither fighter prepared to take risks in a tentative early stages.
Parker, whose sole prior loss came at super middleweight against John Ryder in two years ago after suffering a hand injury during the bout, was participating in his second appearance at light heavyweight.
By the middle rounds, Parker had stayed in contention, causing problems for the favorite, who utilized a protective stance to edge the better stanzas.
The crowd's patience decreased during constant clinching, with Parker going down various instances during clinches.
The underdog ended stronger, but several stanzas were hard to judge. Although, ex-champion the boxing analyst - working with Dazn - had it strongly leaning for the challenger, giving Buatsi just a single round.
The victor moves on, but with the presence of heavy hitter David Benavidez, and Russian champion Bivol ruling the division, the road to world glory - on this evidence - still seems difficult.
Hatton Tribute Inspires Manchester Derby Fight
In the supporting bout, Arthur beat Rea by split-decision in a outstanding all-Manchester battle to win the European light-heavyweight championship.
The arena fell silent for a profoundly moving memorial before the fight as ten bells tolled in memory of Manchester's own Ricky Hatton, who passed away 46 years old in last month.
It was the first major televised boxing event in the location since Hatton's passing. As the concluding sound faded, the stillness became a shout of "there's only one Hatton".
The fighting within the ring equaled the sentiment. The eventual winner was floored by a left hook flush on the jaw in the early round, rising shakily to his feet on the referee's count.
But the traditional red shorts of the fighter soon came forward again. Across the ring, the opponent - in opposing blue - was damaged soon, significant bruising forming under his eye as the pair traded powerful shots.
Rea, 27, connected with strong blows but Arthur, 34, fought fire with fire with effective uppercuts as the action hardly diminished over twelve rounds.
The victor barely secured the result with official scores of draw, 115-113 and 115-112, but each competitor were persistent and full of heart, exactly what their inspiration Hatton stood for.
