British light-heavyweight Buatsi made a winning yet disappointing beginning to life under new promoters with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a split decision in a tight 10-round fight at the boxing arena.
But Parker had his moments, connecting with powerful clean blows in a fight where the approaches didn't complement each other, with constant grabbing disrupting the action.
The scoring judges scored it 96-94 in favor to the winner, with the remaining official a 95-95 draw.
"It wasn't my finest display but what do champions do? They succeed," the victor stated in the arena as he was met by disapproval from the audience.
The Londoner bounced back after his first professional defeat - an thrilling contest with his previous opponent in last winter - to claim a 20th career victory.
Some ringside observers believed the challenger, thirty-one, should have been awarded the win but the Derbyshire fighter endured the second loss of his 28-bout professional journey.
Buatsi Earns Victory in Uneventful Affair
The fighter's advancement has plateaued in recent years through contract problems and considerable time of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now finds himself trying to achieve expectations - maybe in what seems like a ultimate opportunity - under new promotional backing.
He opened tentatively, with both competitors willing to overcommit in a cagey early stages.
Parker, whose sole prior loss came at the lower weight class against his former opponent in two years ago after damaging his hand during the bout, was competing in only his second fight at light-heavyweight.
By the middle rounds, the underdog had stayed in contention, causing problems for Buatsi, who utilized a tight guard to narrowly win the better stanzas.
The crowd's patience diminished amid constant clinching, with the challenger falling to the floor various instances during close exchanges.
The underdog closed well, but several stanzas were challenging to assess. However, ex-champion Carl Frampton - working with the broadcast network - had it significantly in favor for Parker, awarding Buatsi just a single round.
The victor moves on, but with the presence of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the journey to titles - based on this performance - still appears challenging.
Hatton Homage Motivates Local Rivalry Fight
In the co-main event, Lyndon Arthur beat Rea by divided decision in a excellent local rivalry contest to win the European light heavyweight championship.
The arena grew hushed for a deeply poignant homage prior to the bout as a bell ceremony rang in memory of Manchester's own Hatton, who succumbed 46 years old in September.
It was the initial significant broadcast fight night in the urban center since Hatton's death. As the last bell disappeared, the silence gave way to a shout of "only one Ricky Hatton".
The fighting during the bout equaled the emotion. Arthur was floored by a left hook squarely on the jaw in the initial stage, getting up unsteadily to his position on the eight count.
But the Manchester United-red attire of the fighter soon advanced again. Across the ring, the opponent - in rival City blue - was injured soon, noticeable damage appearing under his orbital area as the pair landed punishing blows.
Rea, twenty-seven, delivered effective strikes but Arthur, thirty-four, responded in kind with powerful upward punches as the intensity seldom decreased over the full distance.
The victor narrowly won the decision with official scores of 114-114, close margin and clearer margin, but both fighters were persistent and brave, everything their idol the legend represented.
