UK light-heavyweight Joshua Buatsi made a winning yet unimpressive start to life under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a judges' verdict in a competitive 10-round bout at the boxing arena.
But Parker found success, landing some telling individual punches in a match where the styles didn't complement each other, with excessive holding marring the fight.
The scoring judges judged it 96-94 for to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my finest showing but what defines champions? They succeed," Buatsi stated in the ring as he was met by negative reactions from the audience.
The British fighter bounced back after his first professional defeat - an memorable fight with his previous opponent in last winter - to claim a 20th pro success.
Some ringside observers thought the challenger, thirty-one, merited the victory but the contender endured the second defeat of his 28-match professional journey.
Buatsi Earns Triumph in Slow Encounter
Buatsi's progress has slowed in recent times through management issues and extended periods of inactivity.
Once tipped as the next star of British boxing, he now finds himself trying to fulfil that early promise - possibly in what feels like a ultimate opportunity - under new promotional backing.
He started carefully, with the two boxers prepared to overcommit in a cagey opening few rounds.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in two years ago after breaking his hand mid-fight, was making just his second appearance at light-heavyweight.
By the halfway stage, Parker had stayed in contention, causing problems for Buatsi, who operated with a solid defense to edge the cleaner rounds.
The audience's tolerance diminished because of frequent holding, with Parker going down various instances during close exchanges.
Parker closed well, but many rounds were challenging to assess. Nevertheless, former world champion the boxing analyst - working with Dazn - had it particularly wide for the challenger, scoring for Buatsi just one round.
The victor progresses, but with the caliber of heavy hitter Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - on this evidence - still seems difficult.
Ricky Hatton Tribute Motivates Manchester Derby Fight
In the co-main event, Lyndon Arthur overcame Bradley Rea by split-decision in a outstanding local rivalry contest to capture the continental belt.
The arena fell silent for a deeply poignant tribute before the fight as ten bells sounded in honor of local hero Hatton, who passed away aged 46 in September.
It was the premier televised match card in the urban center since Hatton's death. As the final chime faded, the stillness became a shout of "only one Hatton".
The competition during the bout reflected the feeling. The eventual winner was knocked down by a significant blow squarely on the jaw in the initial stage, rising shakily to his feet on the eight count.
But the traditional red equipment of Arthur soon came forward again. On the opposite side, the opponent - in rival City blue - was injured early, significant bruising developing under his eye as the fighters traded hard punches.
The challenger, 27, connected with strong blows but Arthur, thirty-four, matched the intensity with effective uppercuts as the intensity hardly diminished over twelve rounds.
The victor edged the verdict with official scores of 114-114, 115-113 and clearer margin, but each competitor were determined and full of heart, all the qualities their inspiration Hatton stood for.
