UK light heavyweight Joshua Buatsi made a winning yet underwhelming beginning to life under new promoters with a decision win over Parker in the Manchester arena.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a tight 10-round bout at the boxing arena.
But the challenger had his moments, landing some telling single shots in a match where the approaches never quite clicked, with constant grabbing disrupting the action.
The scoring judges judged it 96-94 in favor to Buatsi, with the third a 95-95.
"It wasn't my finest display but what do champions do? They succeed," Buatsi commented in the ringside as he was met by negative reactions from the spectators.
The British fighter got back to winning after his first professional defeat - an epic battle with Callum Smith in last winter - to earn a twentieth professional win.
Some ringside observers believed the challenger, 31, merited the decision but the British boxer endured the second setback of his 28-match professional journey.
Buatsi Secures Win in Slow Encounter
His career development has plateaued in recent years through management issues and long spells of inactivity.
Previously predicted as the future of British boxing, he now stands trying to achieve expectations - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He began cautiously, with neither fighter willing to be aggressive in a calculated early stages.
Parker, whose only previous defeat came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was competing in only his second bout at the higher weight class.
By the middle rounds, the underdog had kept it close, creating difficulties for the favorite, who utilized a protective stance to edge the cleaner periods.
The audience's tolerance decreased amid constant clinching, with the challenger falling to the floor multiple occasions during clinches.
Parker closed well, but multiple periods were difficult to score. Although, former world champion Carl Frampton - working with the broadcast network - had it particularly wide for the challenger, awarding Buatsi just only one stanza.
The victor moves on, but with the presence of heavy hitter Benavidez, and Russian star Bivol leading the category, the path to championship success - based on this performance - still seems difficult.
Hatton Homage Motivates Local Rivalry Battle
In the secondary fight, Lyndon Arthur beat Bradley Rea by split-decision in a outstanding local rivalry battle to win the continental title.
The arena grew hushed for a deeply poignant homage before the fight as 10 bells rang in remembrance of the city's native Hatton, who passed away at age 46 in last month.
It was the first major televised match card in the location since the passing of Hatton. As the final chime disappeared, the quiet gave way to a chant of "there's just one Hatton".
The fighting within the ring reflected the sentiment. Arthur was sent to the canvas by a powerful punch squarely on the chin in the initial stage, standing uncertainly to his feet on the eight count.
But the red-colored attire of Arthur soon pressed ahead again. On the opposite side, Rea - in rival City blue - was marked up early, significant bruising forming under his orbital area as the fighters exchanged powerful shots.
Rea, twenty-seven, connected with strong blows but the champion, thirty-four, responded in kind with effective uppercuts as the intensity hardly diminished over the full distance.
The victor edged the result with judges scorecards of even score, 115-113 and clearer margin, but each competitor were relentless and full of heart, exactly what their hero the legend stood for.
