UK light-heavyweight Joshua Buatsi made a winning yet unimpressive beginning to his career under new promoters with a decision win over Parker in Manchester.
The Olympic medal winner's activity level likely gained him a majority decision in a competitive ten-round bout at the boxing arena.
But the challenger found success, delivering effective individual punches in a contest where the approaches didn't complement each other, with constant grabbing spoiling the contest.
The scoring judges scored it 96-94 to the winner, with the remaining official a even score.
"It wasn't my finest performance but what defines champions? They win," the victor commented in the ring as he was greeted with boos from the spectators.
The Londoner got back to winning after his maiden career setback - an thrilling contest with Callum Smith in February - to claim a twentieth professional win.
Several boxing experts felt the challenger, 31, merited the victory but the contender endured the second loss of his 28-fight career.
Buatsi Claims Victory in Dull Encounter
Buatsi's progress has slowed in the past few years through contract problems and long spells of lack of fights.
Previously predicted as the future of British boxing, he now stands trying to realize his potential - perhaps in what appears to be a final roll of the dice - under new promotional backing.
He started carefully, with both competitors ready to overcommit in a tentative early stages.
Parker, whose sole prior loss came at super middleweight against his former opponent in two years ago after damaging his hand mid-fight, was participating in his second fight at light heavyweight.
By the fight's midpoint, the underdog had kept it close, causing problems for the favorite, who worked behind a solid defense to narrowly win the more effective stanzas.
The crowd's patience wore thin because of constant clinching, with the challenger slipping to the canvas several times during clinches.
Parker closed well, but several stanzas were difficult to score. However, ex-champion the boxing analyst - commentating on the broadcast network - had it strongly leaning for Parker, giving Buatsi just one round.
Buatsi progresses, but with the presence of hard hitter David Benavidez, and Russian star Bivol ruling the division, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Memorial Fuels All-Manchester Fight
In the secondary fight, Arthur defeated Rea by close verdict in a excellent local rivalry contest to win the European light heavyweight belt.
The venue grew hushed for a profoundly moving tribute ahead of the contest as a bell ceremony sounded in memory of local hero Hatton, who succumbed 46 years old in recently.
It was the initial significant broadcast boxing event in the city since Hatton's passing. As the last bell disappeared, the stillness became a roar of "there's only one Ricky Hatton".
The action within the ring matched the feeling. The eventual winner was knocked down by a left hook squarely on the jaw in the second round, rising shakily to his feet on the count of eight.
But the Manchester United-red attire of the fighter soon advanced again. Across the ring, Rea - in rival City blue - was marked up soon, heavy swelling forming under his orbital area as the fighters exchanged hard punches.
The challenger, twenty-seven, delivered effective strikes but Arthur, thirty-four, matched the intensity with powerful upward punches as the action hardly diminished over the full distance.
The victor narrowly won the verdict with judges scorecards of draw, close margin and 115-112, but the two athletes were persistent and courageous, all the qualities their hero Hatton stood for.
