British light-heavyweight Joshua Buatsi made a winning yet disappointing start to his career under fresh promotional backing with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a majority decision in a tight 10-round fight at the Manchester venue.
But the challenger landed significant shots, delivering effective single shots in a contest where the approaches didn't complement each other, with frequent clinching marring the contest.
The officials had it 96-94 for to Buatsi, with the remaining official a 95-95.
"It wasn't my greatest showing but what do champions do? They prevail," the victor stated in the ring as he was greeted with boos from the spectators.
The British fighter bounced back after his initial pro loss - an epic battle with Callum Smith in February - to secure a 20th career victory.
Various analysts thought the challenger, thirty-one, merited the win but the British boxer experienced the second loss of his 28-fight career.
Buatsi Earns Win in Uneventful Match
Buatsi's progress has plateaued in the past few years through promotional disputes and extended periods of lack of fights.
Previously predicted as the rising talent of British boxing, he now stands trying to realize his potential - maybe in what feels like a final roll of the dice - under fresh management.
He began cautiously, with neither fighter willing to be aggressive in a tentative early stages.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was making just his second fight at light heavyweight.
By the halfway stage, Parker had made it competitive, causing problems for Buatsi, who worked behind a protective stance to edge the cleaner rounds.
The crowd's patience wore thin during frequent holding, with the challenger slipping to the canvas several times during close exchanges.
Parker ended stronger, but several stanzas were difficult to score. However, ex-champion the boxing analyst - providing analysis for the broadcast network - had it strongly leaning for the challenger, giving Buatsi just a single round.
Buatsi progresses, but with the caliber of heavy hitter Benavidez, and Russian champion Bivol dominating the weight class, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Tribute Fuels All-Manchester Fight
In the co-main event, Arthur beat Bradley Rea by divided decision in a outstanding Manchester vs Manchester fight to capture the continental belt.
The arena became quiet for a extremely emotional tribute before the fight as a bell ceremony sounded in memory of Manchester's own Ricky Hatton, who passed away aged 46 in last month.
It was the premier televised boxing event in the urban center since the passing of Hatton. As the last bell disappeared, the silence gave way to a roar of "there's just one Hatton".
The fighting inside the ropes matched the emotion. Arthur was knocked down by a powerful punch squarely on the face in the second round, standing uncertainly to his position on the eight count.
But the red-colored equipment of the fighter soon came forward again. From the other corner, Rea - in competitive blue - was damaged early, noticeable damage forming under his orbital area as the fighters traded hard punches.
Rea, twenty-seven, delivered effective strikes but the champion, 34, fought fire with fire with effective uppercuts as the pace rarely dropped over twelve rounds.
The victor barely secured the decision with official scores of even score, 115-113 and 115-112, but each competitor were determined and brave, everything their hero Hatton embodied.
