British light heavyweight Joshua Buatsi made a winning yet disappointing start to life under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's activity level seemingly secured him a judges' verdict in a tight ten-round contest at the boxing arena.
But the challenger landed significant shots, connecting with powerful individual punches in a match where the styles never quite clicked, with constant grabbing spoiling the action.
Two judges scored it 96-94 in favor to the winner, with the final judge a 95-95.
"It wasn't my greatest showing but what do champions do? They win," Buatsi commented in the ring as he was met by negative reactions from the spectators.
The British fighter returned to winning ways after his first professional defeat - an epic battle with his previous opponent in February - to earn a 20th career victory.
Various analysts believed Parker, thirty-one, merited the victory but the British boxer endured the second loss of his 28-fight career.
Buatsi Secures Win in Dull Affair
Buatsi's progress has stalled in recent times through management issues and considerable time of inactivity.
Earlier forecast as the next star of British boxing, he now stands trying to achieve expectations - possibly in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with the two boxers willing to take risks in a tentative early stages.
Parker, whose single earlier setback came at super-middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was competing in only his second appearance at light heavyweight.
By the middle rounds, the underdog had kept it close, making life awkward for the favorite, who utilized a tight guard to narrowly win the better periods.
The crowd's patience wore thin amid frequent holding, with the challenger slipping to the canvas several times during clinches.
Parker closed well, but several stanzas were difficult to score. However, previous titleholder Carl Frampton - providing analysis for Dazn - had it significantly in favor for Parker, scoring for Buatsi just one round.
The victor moves on, but with the presence of power puncher Benavidez, and Eastern European fighter Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still appears challenging.
Hatton Memorial Fuels Manchester Derby Contest
In the secondary fight, Arthur beat Rea by split-decision in a excellent all-Manchester battle to win the European light-heavyweight title.
The arena fell silent for a extremely emotional homage prior to the bout as ten bells rang in remembrance of local hero Ricky Hatton, who succumbed aged 46 in September.
It was the first major televised match card in the city since Hatton's passing. As the last bell disappeared, the silence gave way to a shout of "there's only one Ricky Hatton".
The fighting within the ring matched the feeling. The eventual winner was floored by a significant blow flush on the face in the early round, standing uncertainly 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, significant bruising appearing under his orbital area as the pair landed hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, responded in kind with effective uppercuts as the pace hardly diminished over the full distance.
The victor edged the decision with judges scorecards of draw, 115-113 and clearer margin, but the two athletes were determined and brave, all the qualities their idol the legend stood for.
