UK light-heavyweight Joshua Buatsi secured a victory yet unimpressive debut to his career under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's punch output likely gained him a split decision in a competitive ten-round bout at the Co-op Live Arena.
But the challenger had his moments, delivering effective clean blows in a contest where the approaches never quite clicked, with excessive holding spoiling the fight.
The officials scored it 96-94 in favor to Buatsi, with the third a 95-95 draw.
"It wasn't my finest showing but how do champions respond? They prevail," Buatsi said in the ring as he was met by boos from the audience.
The Londoner bounced back after his first professional defeat - an epic battle with his previous opponent in February - to earn a 20th pro success.
Several boxing experts thought the challenger, 31, should have been awarded the win but the contender experienced the second defeat of his 28-match professional journey.
The Champion Earns Triumph in Dull Match
His career development has slowed in recent years through contract problems and extended periods of lack of fights.
Earlier forecast as the next star of UK boxing, he now is positioned trying to fulfil that early promise - perhaps in what seems like a ultimate opportunity - under fresh management.
He began cautiously, with the two boxers ready to take risks in a cagey early stages.
The challenger, whose sole prior loss came at super middleweight against his former opponent in two years ago after breaking his hand mid-fight, was participating in his second fight at light heavyweight.
By the middle rounds, Parker had stayed in contention, creating difficulties for Buatsi, who operated with a protective stance to narrowly win the more effective periods.
The audience's tolerance diminished during regular grabbing, with Parker falling to the floor multiple occasions during grappling.
Parker closed well, but many rounds were challenging to assess. Although, ex-champion Carl Frampton - working with the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just only one stanza.
Buatsi advances, but with the presence of power puncher Benavidez, and Russian star Bivol ruling the division, the journey to titles - judging by this showing - still looks steep.
Ricky Hatton Homage Inspires Local Rivalry Fight
In the supporting bout, Lyndon Arthur defeated Bradley Rea by divided decision in a outstanding local rivalry battle to win the continental championship.
The venue became quiet for a deeply poignant homage ahead of the contest as 10 bells tolled in honor of the city's native Hatton, who died aged 46 in last month.
It was the first major televised boxing event in the city since Hatton's death. As the concluding sound faded, the quiet gave way to a chant of "only one Hatton".
The competition within the ring equaled the sentiment. The eventual winner was sent to the canvas by a powerful punch squarely on the jaw in the early round, standing uncertainly to his feet on the count of eight.
But the red-colored equipment of Arthur soon advanced again. Across the ring, the opponent - in opposing blue - was injured quickly, heavy swelling appearing under his eye as the fighters exchanged punishing blows.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, fought fire with fire with effective uppercuts as the pace seldom decreased over 12 rounds.
The victor barely secured the verdict with scoring tallies of even score, 115-113 and 115-112, but the two athletes were relentless and courageous, everything their hero the legend represented.
