UK light heavyweight Joshua Buatsi earned a win yet unimpressive beginning to his career under fresh promotional backing with a points victory over Parker in the Manchester arena.
The Olympic medal winner's activity level appeared to earn him a majority decision in a competitive ten-round contest at the boxing arena.
But Parker landed significant shots, connecting with powerful individual punches in a match where the techniques failed to mesh, 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 finest showing but what defines champions? They win," the victor stated in the ring as he was greeted with boos from the spectators.
The British fighter returned to winning ways after his first professional defeat - an epic battle with his previous opponent in February - to earn a 20th career victory.
Some ringside observers believed the challenger, 31, deserved the decision but the Derbyshire fighter experienced the second loss of his 28-bout career.
The Champion Secures Win in Dull Affair
His career development has stalled in recent years through management issues and extended periods of inactivity.
Once tipped as the next star of the British fight scene, he now is positioned trying to achieve expectations - perhaps in what feels like a final roll of the dice - under fresh management.
He opened tentatively, with the two boxers willing to be aggressive in a calculated opening few rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in two years ago after damaging his hand during the bout, was participating in his second appearance at light heavyweight.
By the middle rounds, the underdog had stayed in contention, creating difficulties for the favorite, who utilized a tight guard to edge the more effective stanzas.
The spectators' acceptance diminished during regular grabbing, with the challenger going down various instances during clinches.
The underdog ended stronger, but multiple periods were hard to judge. However, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, scoring for Buatsi just one round.
Buatsi moves on, but with the presence of power puncher Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - based on this performance - still seems difficult.
Hatton Homage Fuels Manchester Derby Battle
In the secondary fight, Lyndon Arthur beat Bradley Rea by divided decision in a excellent all-Manchester fight to secure the European light heavyweight belt.
The venue fell silent for a profoundly moving tribute ahead of the contest as 10 bells tolled in memory of Manchester's own Hatton, who died at age 46 in September.
It was the initial significant broadcast boxing event in the urban center since Hatton's death. As the last bell ended, the quiet gave way to a chant of "only one Ricky Hatton".
The fighting during the bout equaled the emotion. Arthur was knocked down by a powerful punch squarely on the chin in the early round, getting up unsteadily to his feet on the count of eight.
But the traditional red shorts of Arthur soon came forward again. Across the ring, Rea - in competitive blue - was marked up early, heavy swelling forming under his eye as the fighters landed hard punches.
Rea, 27, delivered effective strikes but the champion, 34, fought fire with fire with powerful upward punches as the pace hardly diminished over 12 rounds.
Arthur barely secured the decision with judges scorecards of even score, 115-113 and wider gap, but the two athletes were determined and full of heart, all the qualities their hero the legend represented.
