British light heavyweight Joshua Buatsi secured a victory yet underwhelming debut to his career under new promoters with a decision win over Parker in Manchester.
The Olympic medal winner's work rate likely gained him a judges' verdict in a close 10-round fight at the boxing arena.
But the challenger had his moments, connecting with powerful single shots in a contest where the techniques never quite clicked, with excessive holding marring the fight.
The officials scored it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my finest display but how do champions respond? They succeed," Buatsi commented in the ringside as he was greeted with boos from the audience.
The British fighter returned to winning ways after his initial pro loss - an epic battle with his previous opponent in last winter - to earn a 20th career victory.
Some ringside observers thought the challenger, 31, merited the victory but the British boxer experienced the second setback of his 28-match career.
Buatsi Claims Victory in Dull Affair
The fighter's advancement has stalled in the past few years through management issues and extended periods of inactivity.
Earlier forecast as the rising talent of British boxing, he now finds himself trying to realize his potential - maybe in what appears to be a final roll of the dice - under recent support.
He began cautiously, with both competitors willing to take risks in a cagey initial rounds.
Parker, whose single earlier setback came at super middleweight against his former opponent in two years ago after suffering a hand injury in the contest, was making just his second fight at light heavyweight.
By the middle rounds, Parker had kept it close, causing problems for the favorite, who operated with a protective stance to edge the more effective rounds.
The spectators' acceptance decreased because of frequent holding, with Parker falling to the floor several times during clinches.
The underdog ended stronger, but several stanzas were challenging to assess. Although, previous titleholder the boxing analyst - commentating on the broadcast network - had it strongly leaning for Parker, scoring for Buatsi just a single round.
Buatsi moves on, but with the presence of hard hitter Benavidez, and Russian champion Dmitry Bivol leading the category, the path to championship success - on this evidence - still looks steep.
Ricky Hatton Homage Inspires Manchester Derby Battle
In the co-main event, Lyndon Arthur defeated Bradley Rea by split-decision in a outstanding Manchester vs Manchester contest to secure the continental title.
The stadium fell silent for a extremely emotional homage prior to the bout as 10 bells tolled in honor of the city's native Hatton, who passed away aged 46 in recently.
It was the initial significant broadcast boxing event in the urban center since Hatton's death. As the concluding sound ended, the quiet became a roar of "there's only one Hatton".
The action within the ring equaled the sentiment. The eventual winner was sent to the canvas by a powerful punch directly to the face in the second round, getting up unsteadily to his footing on the count of eight.
But the Manchester United-red attire of the fighter soon pressed ahead again. Across the ring, the opponent - in competitive blue - was injured early, heavy swelling appearing under his eye as the duo exchanged hard punches.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, fought fire with fire with powerful upward punches as the pace rarely dropped over the full distance.
Arthur narrowly won the verdict with official scores of even score, narrow lead and clearer margin, but the two athletes were relentless and courageous, all the qualities their inspiration Hatton stood for.
