UK light-heavyweight Joshua Buatsi secured a victory yet disappointing beginning to life under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a majority decision in a competitive 10-round fight at the boxing arena.
But the challenger had his moments, landing some telling single shots in a contest where the techniques didn't complement each other, with constant grabbing marring the action.
The officials scored it 96-94 for to the winner, with the third a 95-95.
"It wasn't my greatest performance but what defines champions? They succeed," the victor stated in the ringside as he was greeted with negative reactions from the audience.
The Londoner bounced back after his first professional defeat - an epic battle with his previous opponent in last winter - to secure a 20th pro success.
Several boxing experts believed Parker, 31, merited the win but the contender endured the second setback of his 28-match career.
The Champion Earns Triumph in Dull Match
The fighter's advancement has plateaued in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the future of the British fight scene, he now stands trying to realize his potential - possibly in what appears to be a ultimate opportunity - under fresh management.
He started carefully, with neither fighter willing to overcommit in a tentative early stages.
The challenger, whose only previous defeat came at super-middleweight against his former opponent 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, making life awkward for Buatsi, who worked behind a protective stance to edge the cleaner rounds.
The audience's tolerance wore thin because of regular grabbing, with the challenger slipping to the canvas various instances during grappling.
The underdog closed well, but several stanzas were hard to judge. Although, previous titleholder Carl Frampton - working with the broadcast network - had it significantly in favor for Parker, awarding Buatsi just a single round.
Buatsi advances, but with the presence of hard hitter David Benavidez, and Russian star Bivol dominating the weight class, the road to world glory - on this evidence - still looks steep.
Hatton Tribute Inspires All-Manchester Fight
In the co-main event, Lyndon Arthur beat Rea by close verdict in a terrific local rivalry contest to secure the European light-heavyweight belt.
The stadium grew hushed for a profoundly moving memorial prior to the bout as 10 bells tolled in honor of Manchester's own Ricky Hatton, who passed away 46 years old in September.
It was the premier televised match card in the location since the passing of Hatton. As the final chime faded, the stillness transitioned to a roar of "only one Hatton".
The fighting within the ring matched the sentiment. Arthur was knocked down by a significant blow directly to the chin in the initial stage, standing uncertainly to his footing on the count of eight.
But the traditional red shorts of the fighter soon pressed ahead again. From the other corner, the opponent - in opposing blue - was damaged quickly, heavy swelling forming under his eye as the fighters landed hard punches.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, responded in kind with effective uppercuts as the action seldom decreased over 12 rounds.
Arthur edged the result with judges scorecards of 114-114, close margin and 115-112, but the two athletes were relentless and full of heart, exactly what their hero Hatton embodied.
