British light heavyweight Joshua Buatsi earned a win yet disappointing beginning to life under fresh promotional backing with a points victory over Parker in the Manchester arena.
The Olympic bronze medallist's work rate likely gained him a judges' verdict in a competitive ten-round bout at the Co-op Live Arena.
But Parker found success, delivering effective clean blows in a fight where the styles didn't complement each other, with constant grabbing disrupting the action.
Two judges scored it 96-94 in favor to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my best performance but what defines champions? They succeed," Buatsi stated in the ringside as he was met by negative reactions from the audience.
The Londoner got back to winning after his initial pro loss - an memorable fight with his previous opponent in February - to claim a 20th career victory.
Various analysts felt the challenger, 31, merited the victory but the contender suffered the second loss of his 28-match career.
Buatsi Secures Win in Dull Affair
The fighter's advancement has stalled in the past few years through management issues and extended periods of inactivity.
Once tipped as the future of British boxing, he now stands trying to fulfil that early promise - perhaps in what seems like a final roll of the dice - under recent support.
He started carefully, with both competitors willing to be aggressive in a tentative early stages.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after damaging his hand mid-fight, was making just his second appearance at light-heavyweight.
By the middle rounds, Parker had stayed in contention, causing problems for the favorite, who worked behind a tight guard to barely take the better stanzas.
The spectators' acceptance diminished amid frequent holding, with Parker going down several times during close exchanges.
The underdog ended stronger, but many rounds were hard to judge. Nevertheless, previous titleholder the boxing analyst - providing analysis for the broadcast network - had it particularly wide for Parker, awarding Buatsi just one round.
Buatsi advances, but with the caliber of power puncher Benavidez, and Russian star Dmitry Bivol dominating the weight class, the path to championship success - on this evidence - still appears challenging.
Ricky Hatton Homage Inspires Local Rivalry Contest
In the co-main event, Lyndon Arthur overcame Bradley Rea by divided decision in a terrific all-Manchester fight to win the continental title.
The stadium fell silent for a profoundly moving tribute ahead of the contest as a bell ceremony sounded in honor of the city's native Hatton, who succumbed 46 years old in recently.
It was the initial significant broadcast boxing event in the location since the passing of Hatton. As the concluding sound ended, the silence gave way to a chant of "only one Hatton".
The action during the bout matched the feeling. The eventual winner was floored by a powerful punch squarely on the jaw in the early round, rising shakily to his position on the referee's count.
But the traditional red shorts of the fighter soon came forward again. From the other corner, Rea - in opposing blue - was damaged early, noticeable damage developing under his orbital area as the pair exchanged hard punches.
Rea, twenty-seven, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the action hardly diminished over the full distance.
Arthur narrowly won the result with judges scorecards of 114-114, close margin and clearer margin, but each competitor were determined and full of heart, exactly what their hero the legend stood for.
