British light-heavyweight Joshua Buatsi made a winning yet unimpressive debut to his career under new promoters with a points victory over Parker in the Manchester arena.
The Olympic medal winner's activity level seemingly secured him a split decision in a tight ten-round bout at the Co-op Live Arena.
But Parker found success, connecting with powerful single shots in a match where the styles never quite clicked, with constant grabbing disrupting the fight.
Two judges had it 96-94 in favor to the winner, with the final judge a 95-95 draw.
"It wasn't my greatest performance but what do champions do? They prevail," the victor said in the ring as he was faced negative reactions from the audience.
The British fighter got back to winning after his maiden career setback - an memorable fight with his previous opponent in February - to claim a 20th career victory.
Various analysts felt the challenger, thirty-one, merited the victory but the Derbyshire fighter endured the second defeat of his 28-bout professional journey.
The Champion Claims Win in Uneventful Affair
His career development has plateaued in the past few years through promotional disputes and long spells of inactivity.
Once tipped as the next star of British boxing, he now stands trying to realize his potential - maybe in what seems like a last chance - under recent support.
He opened tentatively, with neither fighter ready to be aggressive in a cagey initial rounds.
Parker, whose single earlier setback came at the lower weight class against John Ryder in two years ago after damaging his hand during the bout, was competing in only his second bout at light heavyweight.
By the middle rounds, Parker had stayed in contention, creating difficulties for Buatsi, who utilized a solid defense to barely take the more effective stanzas.
The spectators' acceptance diminished during constant clinching, with the challenger falling to the floor several times during close exchanges.
The underdog closed well, but multiple periods were hard to judge. Although, former world champion Carl Frampton - commentating on the broadcast network - had it significantly in favor for Parker, giving Buatsi just only one stanza.
Buatsi progresses, but with the caliber of heavy hitter David Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - judging by this showing - still looks steep.
Hatton Homage Motivates All-Manchester Fight
In the co-main event, Arthur beat Bradley Rea by split-decision in a terrific local rivalry contest to capture the continental championship.
The venue became quiet for a extremely emotional homage before the fight as 10 bells sounded in remembrance of local hero Ricky Hatton, who died 46 years old in recently.
It was the premier televised match card in the city since Hatton's death. As the final chime faded, the silence became a shout of "there's only one Hatton".
The competition inside the ropes matched the sentiment. The eventual winner was knocked down by a left hook directly to the chin in the early round, standing uncertainly to his footing on the count of eight.
But the red-colored shorts of Arthur soon advanced again. Across the ring, the opponent - in opposing blue - was damaged early, noticeable damage forming under his orbital area as the pair traded hard punches.
Rea, 27, delivered effective strikes but the champion, thirty-four, matched the intensity with powerful upward punches as the pace hardly diminished over 12 rounds.
Arthur edged the result with judges scorecards of 114-114, close margin and clearer margin, but both fighters were determined and full of heart, everything their idol the legend represented.
