British light heavyweight Joshua Buatsi secured a victory yet underwhelming debut to his career under new promoters with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a majority decision in a close 10-round contest at the Manchester venue.
But the challenger found success, landing some telling individual punches in a contest where the techniques never quite clicked, with frequent clinching disrupting the action.
Two judges scored it 96-94 for to the winner, with the final judge a even score.
"It wasn't my finest performance but how do champions respond? They win," Buatsi stated in the arena as he was greeted with boos from the spectators.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in last winter - to earn a twentieth professional win.
Various analysts felt the challenger, 31, deserved the win but the contender suffered the second defeat of his 28-bout professional journey.
Buatsi Claims Victory in Uneventful Encounter
His career development has slowed in recent times through contract problems and extended periods of lack of fights.
Previously predicted as the next star of the British fight scene, he now stands trying to achieve expectations - perhaps in what appears to be a last chance - under new promotional backing.
He started carefully, with both competitors willing to overcommit in a cagey opening few rounds.
The challenger, whose single earlier setback came at super middleweight against John Ryder in two years ago after suffering a hand injury in the contest, was competing in only his second bout at light-heavyweight.
By the middle rounds, Parker had made it competitive, making life awkward for Buatsi, who operated with a solid defense to barely take the better stanzas.
The spectators' acceptance decreased because of constant clinching, with the challenger going down several times during clinches.
Parker ended stronger, but several stanzas were difficult to score. However, previous titleholder the boxing analyst - working with the broadcast network - had it particularly wide for the challenger, giving Buatsi just a single round.
Buatsi progresses, but with the likes of power puncher Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the path to championship success - judging by this showing - still seems difficult.
Hatton Tribute Fuels Local Rivalry Battle
In the secondary fight, Arthur beat Bradley Rea by close verdict in a outstanding local rivalry fight to win the European light heavyweight title.
The venue fell silent for a extremely emotional memorial prior to the bout as 10 bells rang in honor of the city's native Ricky Hatton, who passed away 46 years old in September.
It was the first major televised boxing event in the city since the passing of Hatton. As the last bell faded, the quiet transitioned to a shout of "only one Ricky Hatton".
The fighting during the bout reflected the sentiment. Arthur was floored by a significant blow flush on the chin in the early round, standing uncertainly to his feet on the eight count.
But the red-colored shorts of Arthur soon came forward again. From the other corner, the opponent - in competitive blue - was damaged quickly, significant bruising forming under his eye as the duo landed powerful shots.
Rea, 27, connected with strong blows but the champion, thirty-four, fought fire with fire with effective uppercuts as the pace seldom decreased over the full distance.
The victor edged the result with official scores of 114-114, close margin and 115-112, but each competitor were relentless and courageous, everything their inspiration the legend stood for.
