British light-heavyweight Joshua Buatsi made a winning yet unimpressive beginning to his career under fresh promotional backing with a decision win over Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a close ten-round bout at the boxing arena.
But Parker had his moments, landing some telling single shots in a contest where the styles didn't complement each other, with constant grabbing disrupting the action.
The scoring judges judged it 96-94 to Buatsi, with the third a 95-95.
"It wasn't my greatest performance but what do champions do? They succeed," the victor said in the ring as he was met by boos from the audience.
The British fighter bounced back after his first professional defeat - an memorable fight with his previous opponent in last winter - to secure a 20th pro success.
Various analysts believed the challenger, thirty-one, merited the win but the Derbyshire fighter suffered the second setback of his 28-match career.
The Champion Claims Victory in Uneventful Affair
Buatsi's progress has stalled in recent years through contract problems and considerable time of inactivity.
Earlier forecast as the next star of the British fight scene, he now stands trying to realize his potential - perhaps in what feels like a ultimate opportunity - under new promotional backing.
He started carefully, with the two boxers prepared to take risks in a calculated initial rounds.
The challenger, whose single earlier setback came at super middleweight against his former opponent in two years ago after suffering a hand injury mid-fight, was making just his second fight at the higher weight class.
By the middle rounds, Parker had kept it close, making life awkward for the favorite, who utilized a solid defense to edge the more effective rounds.
The audience's tolerance wore thin amid frequent holding, with the challenger falling to the floor multiple occasions during grappling.
The underdog finished the stronger, but several stanzas were difficult to score. However, former world champion Carl Frampton - providing analysis for the broadcast network - had it strongly leaning for the challenger, awarding Buatsi just a single round.
Buatsi advances, but with the caliber of heavy hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Ricky Hatton Memorial Inspires Manchester Derby Battle
In the supporting bout, Lyndon Arthur beat Rea by split-decision in a excellent local rivalry battle to capture the European light heavyweight belt.
The stadium grew hushed for a deeply poignant homage prior to the bout as 10 bells tolled in memory of Manchester's own Hatton, who passed away aged 46 in last month.
It was the initial significant broadcast boxing event in the city since Hatton's death. As the final chime ended, the stillness gave way to a roar of "there's only one Ricky Hatton".
The competition within the ring matched the emotion. Arthur was sent to the canvas by a powerful punch squarely on the chin in the initial stage, getting up unsteadily to his position on the referee's count.
But the traditional red attire of Arthur soon advanced again. Across the ring, the opponent - in competitive blue - was marked up soon, noticeable damage developing under his orbital area as the fighters exchanged hard punches.
The challenger, 27, connected with strong blows but the champion, 34, matched the intensity with effective uppercuts as the action rarely dropped over the full distance.
The victor narrowly won the verdict with scoring tallies of draw, 115-113 and 115-112, but each competitor were determined and courageous, everything their inspiration Hatton embodied.
