British light-heavyweight Joshua Buatsi made a winning yet underwhelming beginning to his career under fresh promotional backing with a unanimous decision over Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a majority decision in a tight ten-round fight at the Co-op Live Arena.
But the challenger found success, connecting with powerful clean blows in a fight where the approaches never quite clicked, with constant grabbing disrupting the fight.
The scoring judges scored it 96-94 for to Buatsi, with the third a 95-95.
"It wasn't my greatest display but how do champions respond? They prevail," the victor stated in the arena as he was faced negative reactions from the audience.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with his previous opponent in last winter - to claim a 20th career victory.
Several boxing experts believed Parker, thirty-one, should have been awarded the victory but the contender experienced the second loss of his 28-bout career.
Buatsi Earns Triumph in Slow Match
Buatsi's progress has stalled in the past few years through contract problems and considerable time of lack of fights.
Previously predicted as the future of the British fight scene, he now finds himself trying to realize his potential - possibly in what seems like a last chance - under recent support.
He started carefully, with neither fighter prepared to overcommit in a cagey early stages.
The challenger, 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 bout at light heavyweight.
By the halfway stage, the underdog had stayed in contention, causing problems for Buatsi, who utilized a tight guard to narrowly win the better stanzas.
The crowd's patience decreased because of frequent holding, with Parker going down several times during clinches.
Parker closed well, but many rounds were hard to judge. However, ex-champion the boxing analyst - providing analysis for the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
Buatsi advances, but with the likes of power puncher David Benavidez, and Eastern European fighter Bivol dominating the weight class, the path to championship success - judging by this showing - still appears challenging.
Ricky Hatton Tribute Inspires Local Rivalry Fight
In the secondary fight, Lyndon Arthur overcame Rea by close verdict in a outstanding Manchester vs Manchester fight to secure the European light-heavyweight championship.
The arena grew hushed for a extremely emotional memorial prior to the bout as a bell ceremony rang in memory of Manchester's own Hatton, who passed away at age 46 in last month.
It was the first major televised fight night in the location since the passing of Hatton. As the concluding sound disappeared, the stillness transitioned to a shout of "only one Hatton".
The competition during the bout matched the feeling. The eventual winner was floored by a powerful punch squarely on the face in the early round, rising shakily to his position on the count of eight.
But the red-colored equipment of Arthur soon advanced again. From the other corner, the opponent - in competitive blue - was injured soon, heavy swelling appearing under his orbital area as the fighters landed punishing blows.
Rea, 27, delivered effective strikes but Arthur, 34, fought fire with fire with stinging uppercuts as the action rarely dropped over the full distance.
The victor narrowly won the decision with judges scorecards of even score, close margin and wider gap, but each competitor were relentless and full of heart, all the qualities their inspiration Hatton embodied.
