UK light heavyweight Joshua Buatsi secured a victory yet underwhelming start to life under new promoters with a unanimous decision over Parker in Manchester.
The Olympic medal winner's work rate likely gained him a majority decision in a competitive 10-round contest at the boxing arena.
But the challenger found success, delivering effective individual punches in a match where the approaches didn't complement each other, with frequent clinching disrupting the action.
The scoring judges scored it 96-94 for to Buatsi, with the final judge a 95-95 draw.
"It wasn't my finest showing but what do champions do? They prevail," the victor said in the ringside as he was greeted with boos from the audience.
The Londoner bounced back after his initial pro loss - an memorable fight with his previous opponent in last winter - to secure a twentieth professional win.
Some ringside observers felt the challenger, 31, merited the win but the contender suffered the second defeat of his 28-match professional journey.
The Champion Claims Triumph in Dull Match
Buatsi's progress has stalled in the past few years through management issues and considerable time of inactivity.
Previously predicted as the next star of UK boxing, he now stands trying to fulfil that early promise - perhaps in what appears to be a ultimate opportunity - under fresh management.
He opened tentatively, with neither fighter willing to overcommit in a calculated initial rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after breaking his hand in the contest, was making just his second fight at light-heavyweight.
By the middle rounds, the underdog had made it competitive, creating difficulties for Buatsi, who worked behind a solid defense to barely take the cleaner periods.
The audience's tolerance diminished amid regular grabbing, with Parker going down multiple occasions during grappling.
The underdog closed well, but multiple periods were hard to judge. However, former world champion the boxing analyst - working with the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just one round.
The victor advances, but with the caliber of heavy hitter Benavidez, and Russian star Bivol ruling the division, the journey to titles - on this evidence - still seems difficult.
Hatton Homage Fuels Local Rivalry Contest
In the supporting bout, Lyndon Arthur overcame Bradley Rea by split-decision in a terrific local rivalry contest to secure the continental title.
The stadium grew hushed for a deeply poignant tribute ahead of the contest as ten bells rang in remembrance of Manchester's own Hatton, who passed away at age 46 in last month.
It was the initial significant broadcast match card in the city since the passing of Hatton. As the concluding sound faded, the silence gave way to a chant of "there's only one Ricky Hatton".
The competition within the ring matched the emotion. The eventual winner was sent to the canvas by a left hook flush on the face in the initial stage, standing uncertainly to his position on the count of eight.
But the red-colored shorts of the fighter soon pressed ahead again. Across the ring, Rea - in rival City blue - was damaged soon, heavy swelling forming under his eye as the duo exchanged powerful shots.
Rea, 27, landed power punches but the champion, 34, fought fire with fire with powerful upward punches as the pace hardly diminished over 12 rounds.
Arthur narrowly won the decision with scoring tallies of even score, narrow lead and 115-112, but each competitor were determined and full of heart, all the qualities their inspiration the legend represented.
