British light heavyweight Joshua Buatsi earned a win yet unimpressive start to his career under new promoters with a points victory over Parker in Manchester.
The Olympic bronze medallist's activity level likely gained him a split decision in a close ten-round fight at the boxing arena.
But the challenger had his moments, delivering effective single shots in a contest where the approaches never quite clicked, with constant grabbing marring the fight.
The officials scored it 96-94 to Buatsi, with the final judge a even score.
"It wasn't my finest showing but what do champions do? They prevail," the victor stated in the ring as he was met by negative reactions from the crowd.
The Londoner returned to winning ways after his first professional defeat - an epic battle with his previous opponent in last winter - to claim a 20th pro success.
Various analysts thought the challenger, 31, deserved the win but the Derbyshire fighter suffered the second setback of his 28-match career.
The Champion Secures Win in Slow Match
The fighter's advancement has plateaued in recent times through promotional disputes and long spells of inactivity.
Previously predicted as the rising talent of the British fight scene, he now stands trying to realize his potential - maybe in what feels like a last chance - under recent support.
He began cautiously, with neither fighter willing to be aggressive in a calculated early stages.
Parker, whose single earlier setback came at the lower weight class against his former opponent in two years ago after suffering a hand injury during the bout, was competing in only his second fight at light-heavyweight.
By the middle rounds, Parker had kept it close, causing problems for the favorite, who operated with a tight guard to barely take the cleaner rounds.
The crowd's patience decreased because of frequent holding, with Parker slipping to the canvas various instances during clinches.
The underdog closed well, but many rounds were challenging to assess. However, ex-champion the boxing analyst - commentating on Dazn - had it strongly leaning for Parker, giving Buatsi just one round.
Buatsi moves on, but with the presence of hard hitter Benavidez, and Russian champion Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still appears challenging.
Hatton Memorial Motivates All-Manchester Contest
In the supporting bout, Lyndon Arthur overcame Bradley Rea by divided decision in a terrific Manchester vs Manchester fight to capture the European light-heavyweight championship.
The stadium grew hushed for a extremely emotional homage ahead of the contest as a bell ceremony tolled in remembrance of the city's native Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast fight night in the location since the passing of Hatton. As the last bell ended, the stillness became a shout of "only one Hatton".
The action during the bout matched the emotion. The eventual winner was floored by a significant blow directly to the jaw in the second round, rising shakily to his position on the eight count.
But the Manchester United-red equipment of the fighter soon pressed ahead again. From the other corner, Rea - in competitive blue - was damaged soon, heavy swelling developing under his orbital area as the pair landed powerful shots.
Rea, twenty-seven, delivered effective strikes but the champion, 34, matched the intensity with effective uppercuts as the intensity seldom decreased over twelve rounds.
The victor narrowly won the result with scoring tallies of 114-114, close margin and clearer margin, but each competitor were determined and brave, exactly what their hero Hatton represented.
