British light-heavyweight Joshua Buatsi made a winning yet underwhelming start to his career under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic medal winner's punch output seemingly secured him a majority decision in a tight 10-round contest at the Co-op Live Arena.
But Parker found success, connecting with powerful single shots in a fight where the approaches never quite clicked, with frequent clinching disrupting the action.
The scoring judges scored it 96-94 in favor to Buatsi, with the third a even score.
"It wasn't my best showing but what do champions do? They prevail," Buatsi said in the arena as he was faced disapproval from the audience.
The British fighter got back to winning after his maiden career setback - an memorable fight with Callum Smith in last winter - to claim a 20th career victory.
Some ringside observers believed the challenger, 31, should have been awarded the decision but the British boxer experienced the second defeat of his 28-match professional journey.
The Champion Claims Triumph in Uneventful Affair
The fighter's advancement has stalled in the past few years through contract problems and long spells of lack of fights.
Earlier forecast as the next star of the British fight scene, he now stands trying to fulfil that early promise - maybe in what seems like a final roll of the dice - under fresh management.
He started carefully, with both competitors prepared to overcommit in a cagey early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after breaking his hand during the bout, was competing in only his second appearance at light heavyweight.
By the halfway stage, the underdog had made it competitive, creating difficulties for the favorite, who utilized a solid defense to narrowly win the better stanzas.
The crowd's patience diminished during constant clinching, with Parker falling to the floor various instances during close exchanges.
Parker ended stronger, but several stanzas were hard to judge. Although, previous titleholder Carl Frampton - commentating on the broadcast network - had it particularly wide for Parker, awarding Buatsi just only one stanza.
Buatsi moves on, but with the caliber of hard hitter Benavidez, and Eastern European fighter Dmitry Bivol leading the category, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Tribute Fuels Manchester Derby Fight
In the secondary fight, Arthur beat Bradley Rea by close verdict in a outstanding local rivalry contest to capture the European light-heavyweight title.
The stadium grew hushed for a deeply poignant homage prior to the bout as 10 bells sounded in honor of the city's native Hatton, who passed away at age 46 in September.
It was the first major televised match card in the location since the passing of Hatton. As the final chime disappeared, the silence gave way to a chant of "there's just one Ricky Hatton".
The action within the ring equaled the feeling. The eventual winner was knocked down by a significant blow directly to the jaw in the early round, getting up unsteadily to his feet on the referee's count.
But the Manchester United-red shorts of the fighter soon came forward again. On the opposite side, the opponent - in opposing blue - was marked up soon, heavy swelling appearing under his eye as the pair traded powerful shots.
Rea, twenty-seven, landed power punches but the champion, thirty-four, responded in kind with powerful upward punches as the intensity hardly diminished over 12 rounds.
Arthur barely secured the verdict with scoring tallies of 114-114, close margin and wider gap, but each competitor were determined and full of heart, everything their inspiration the legend embodied.
