UK light-heavyweight Buatsi made a winning yet unimpressive beginning to life under recent management with a decision win over Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a majority decision in a competitive 10-round fight at the Manchester venue.
But Parker found success, landing some telling single shots in a contest where the approaches didn't complement each other, with constant grabbing spoiling the contest.
The officials had it 96-94 in favor to Buatsi, with the remaining official a 95-95.
"It wasn't my best performance but how do champions respond? They prevail," the victor stated in the arena as he was faced negative reactions from the spectators.
The Londoner bounced back after his initial pro loss - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts felt the challenger, thirty-one, should have been awarded the win but the Derbyshire fighter suffered the second defeat of his 28-fight career.
The Champion Claims Triumph in Slow Match
His career development has stalled in recent times through promotional disputes and long spells of inactivity.
Once tipped as the future of the British fight scene, he now stands trying to fulfil that early promise - perhaps in what appears to be a ultimate opportunity - under new promotional backing.
He started carefully, with neither fighter ready to overcommit in a tentative opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in two years ago after suffering a hand injury in the contest, was making just his second appearance at light-heavyweight.
By the fight's midpoint, the underdog had made it competitive, causing problems for the favorite, who utilized a protective stance to narrowly win the more effective rounds.
The audience's tolerance diminished amid regular grabbing, with the challenger going down several times during clinches.
The underdog ended stronger, but multiple periods were challenging to assess. Although, previous titleholder the boxing analyst - commentating on the broadcast network - had it strongly leaning for Parker, awarding Buatsi just one round.
Buatsi progresses, but with the caliber of power puncher David Benavidez, and Russian star Bivol ruling the division, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Tribute Motivates Local Rivalry Battle
In the supporting bout, Lyndon Arthur defeated Bradley Rea by divided decision in a terrific all-Manchester fight to win the European light-heavyweight belt.
The stadium fell silent for a profoundly moving memorial before the fight as a bell ceremony sounded in honor of the city's native Hatton, who died at age 46 in last month.
It was the premier televised boxing event in the urban center since Hatton's death. As the concluding sound disappeared, the quiet transitioned to a roar of "only one Ricky Hatton".
The action within the ring reflected the sentiment. Arthur was knocked down by a significant blow squarely on the chin in the second round, standing uncertainly to his feet on the referee's count.
But the Manchester United-red equipment of the fighter soon advanced again. From the other corner, Rea - in rival City blue - was damaged soon, significant bruising developing under his orbital area as the fighters traded hard punches.
Rea, 27, connected with strong blows but Arthur, thirty-four, matched the intensity with stinging uppercuts as the intensity rarely dropped over 12 rounds.
The victor edged the verdict with judges scorecards of even score, close margin and wider gap, but each competitor were persistent and full of heart, exactly what their inspiration the legend embodied.
