UK light-heavyweight Joshua Buatsi secured a victory yet disappointing debut to his career under recent management with a unanimous decision over Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a split decision in a tight ten-round contest at the Co-op Live Arena.
But Parker landed significant shots, delivering effective single shots in a match where the approaches didn't complement each other, with constant grabbing marring the action.
The officials scored it 96-94 to Buatsi, with the final judge a 95-95 draw.
"It wasn't my greatest display but what do champions do? They win," Buatsi stated in the ring as he was greeted with negative reactions from the crowd.
The Londoner returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in last winter - to secure a twentieth professional win.
Several boxing experts believed the challenger, thirty-one, merited the decision but the contender suffered the second setback of his 28-match professional journey.
Buatsi Earns Win in Slow Match
His career development has plateaued in recent times through management issues and extended periods of inactivity.
Earlier forecast as the next star of the British fight scene, he now stands trying to realize his potential - maybe in what feels like a final roll of the dice - under new promotional backing.
He began cautiously, with both competitors prepared to be aggressive in a tentative early stages.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand mid-fight, was participating in his second fight at light heavyweight.
By the fight's midpoint, Parker had stayed in contention, causing problems for the favorite, who operated with a solid defense to narrowly win the better rounds.
The crowd's patience decreased amid frequent holding, with Parker falling to the floor several times during clinches.
Parker finished the stronger, but multiple periods were hard to judge. Although, previous titleholder Carl Frampton - commentating on Dazn - had it particularly wide for the challenger, awarding Buatsi just one round.
Buatsi moves on, but with the caliber of heavy hitter Benavidez, and Russian star Dmitry Bivol dominating the weight class, the journey to titles - judging by this showing - still seems difficult.
Ricky Hatton Homage Fuels Local Rivalry Fight
In the co-main event, Arthur defeated Rea by split-decision in a terrific local rivalry fight to secure the European light-heavyweight belt.
The venue grew hushed for a extremely emotional tribute prior to the bout as 10 bells tolled in memory of Manchester's own Ricky Hatton, who passed away 46 years old in recently.
It was the premier televised match card in the city since the passing of Hatton. As the concluding sound ended, the stillness gave way to a shout of "there's only one Ricky Hatton".
The fighting within the ring matched the sentiment. Arthur was sent to the canvas by a powerful punch directly to the jaw in the second round, rising shakily to his footing on the eight count.
But the traditional red equipment of Arthur soon came forward again. From the other corner, Rea - in competitive blue - was damaged quickly, heavy swelling appearing under his eye as the pair exchanged punishing blows.
The challenger, twenty-seven, connected with strong blows but Arthur, thirty-four, responded in kind with stinging uppercuts as the action seldom decreased over twelve rounds.
The victor narrowly won the result with scoring tallies of even score, 115-113 and clearer margin, but both fighters were determined and brave, everything their hero Hatton stood for.
