UK light-heavyweight Joshua Buatsi made a winning yet underwhelming start to life under new promoters with a unanimous decision over Parker in the Manchester arena.
The Olympic bronze medallist's activity level likely gained him a split decision in a tight ten-round contest at the Co-op Live Arena.
But Parker landed significant shots, landing some telling individual punches in a fight where the techniques failed to mesh, with frequent clinching marring the fight.
The scoring judges had it 96-94 to the winner, with the third a 95-95.
"It wasn't my finest showing but what do champions do? They succeed," the victor said in the ringside as he was faced 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 claim a twentieth professional win.
Various analysts felt Parker, 31, merited the victory but the contender experienced the second loss of his 28-match professional journey.
The Champion Secures Triumph in Slow Match
The fighter's advancement has stalled in recent times through contract problems and extended periods of inactivity.
Earlier forecast as the rising talent of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what seems like a last chance - under new promotional backing.
He began cautiously, with both competitors ready to be aggressive in a calculated initial rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after damaging his hand in the contest, was participating in his second bout at light-heavyweight.
By the middle rounds, the underdog had kept it close, causing problems for Buatsi, who operated with a tight guard to narrowly win the better stanzas.
The crowd's patience wore thin because of constant clinching, with Parker going down several times during grappling.
The underdog finished the stronger, but several stanzas were challenging to assess. Although, former world champion the boxing analyst - working with Dazn - had it particularly wide for Parker, scoring for Buatsi just one round.
Buatsi moves on, but with the presence of power puncher Benavidez, and Eastern European fighter Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still seems difficult.
Ricky Hatton Tribute Motivates Local Rivalry Contest
In the secondary fight, Arthur defeated Bradley Rea by close verdict in a excellent Manchester vs Manchester fight to win the European light-heavyweight championship.
The venue became quiet for a extremely emotional memorial prior to the bout as 10 bells sounded in memory of the city's native Hatton, who passed away at age 46 in September.
It was the initial significant broadcast match card in the urban center since Hatton's death. As the last bell ended, the stillness became a chant of "there's only one Hatton".
The competition within the ring matched the sentiment. The eventual winner was floored by a significant blow directly to the chin in the initial stage, rising shakily to his footing on the count of eight.
But the Manchester United-red equipment of Arthur soon advanced again. Across the ring, Rea - in competitive blue - was injured quickly, noticeable damage developing under his face as the pair landed powerful shots.
Rea, twenty-seven, connected with strong blows but the champion, thirty-four, responded in kind with stinging uppercuts as the pace seldom decreased over 12 rounds.
The victor barely secured the decision with judges scorecards of 114-114, narrow lead and wider gap, but each competitor were relentless and brave, everything their inspiration the legend stood for.
