UK light heavyweight Joshua Buatsi earned a win yet underwhelming start to his career under fresh promotional backing with a unanimous decision over Parker in Manchester.
The Olympic bronze medallist's work rate seemingly secured him a split decision in a competitive 10-round fight at the boxing arena.
But Parker landed significant shots, landing some telling clean blows in a contest where the approaches didn't complement each other, with constant grabbing spoiling the action.
The scoring judges scored it 96-94 to the winner, with the final judge a 95-95.
"It wasn't my best performance but how do champions respond? They win," Buatsi said in the arena as he was greeted with boos from the audience.
The Londoner returned to winning ways after his first professional defeat - an memorable fight with Callum Smith in last winter - to claim a 20th pro success.
Some ringside observers believed the challenger, thirty-one, deserved the decision but the contender experienced the second loss of his 28-bout professional journey.
The Champion Secures Win in Uneventful Encounter
His career development has stalled in the past few years through management issues and considerable time of inactivity.
Once tipped as the next star of UK boxing, he now is positioned trying to fulfil that early promise - possibly in what appears to be a last chance - under new promotional backing.
He started carefully, with the two boxers willing to be aggressive in a cagey early stages.
Parker, whose sole prior loss came at the lower weight class against his former opponent in two years ago after damaging his hand during the bout, was competing in only his second appearance at light heavyweight.
By the halfway stage, the underdog had stayed in contention, creating difficulties for the favorite, who worked behind a protective stance to narrowly win the more effective periods.
The crowd's patience diminished during constant clinching, with the challenger falling to the floor various instances during close exchanges.
The underdog finished the stronger, but many rounds were difficult to score. However, former world champion Carl Frampton - providing analysis for Dazn - had it strongly leaning for the challenger, awarding Buatsi just only one stanza.
Buatsi moves on, but with the presence of hard hitter Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - based on this performance - still looks steep.
Ricky Hatton Memorial Motivates Manchester Derby Contest
In the supporting bout, Arthur beat Rea by close verdict in a terrific local rivalry fight to capture the European light heavyweight title.
The arena grew hushed for a extremely emotional homage ahead of the contest as 10 bells rang in remembrance of local hero Ricky Hatton, who died 46 years old in September.
It was the first major televised match card in the urban center since Hatton's death. As the concluding sound faded, the quiet became a roar of "there's only one Ricky Hatton".
The fighting during the bout reflected the feeling. The eventual winner was sent to the canvas by a significant blow flush on the chin in the early round, getting up unsteadily to his feet on the count of eight.
But the red-colored equipment of the fighter soon advanced again. On the opposite side, the opponent - in rival City blue - was marked up early, noticeable damage appearing under his face as the duo traded powerful shots.
The challenger, 27, delivered effective strikes but the champion, 34, matched the intensity with effective uppercuts as the pace hardly diminished over the full distance.
The victor barely secured the result with scoring tallies of 114-114, close margin and 115-112, but the two athletes were relentless and courageous, all the qualities their inspiration Hatton stood for.
