British light heavyweight Joshua Buatsi earned a win yet underwhelming debut to his career under fresh promotional backing with a decision win over Parker in the Manchester arena.
The Olympic medal winner's activity level likely gained him a split decision in a competitive 10-round contest at the boxing arena.
But the challenger had his moments, landing some telling clean blows in a contest where the approaches never quite clicked, with frequent clinching spoiling the contest.
Two judges judged it 96-94 in favor to the winner, with the remaining official a 95-95.
"It wasn't my best performance but how do champions respond? They win," the victor said in the ring as he was faced disapproval from the audience.
The British fighter bounced back after his maiden career setback - an thrilling contest with his previous opponent in last winter - to claim a 20th career victory.
Various analysts felt the challenger, 31, deserved the decision but the Derbyshire fighter endured the second setback of his 28-match professional journey.
The Champion Claims Triumph in Uneventful Affair
The fighter's advancement has plateaued in recent times through promotional disputes and considerable time of inactivity.
Once tipped as the next star of British boxing, he now stands trying to realize his potential - possibly in what seems like a last chance - under fresh management.
He began cautiously, with neither fighter willing to take risks in a calculated initial rounds.
Parker, whose single earlier setback came at super-middleweight against John Ryder in two years ago after damaging his hand mid-fight, was making just his second appearance at light heavyweight.
By the fight's midpoint, Parker had kept it close, creating difficulties for Buatsi, who operated with a tight guard to barely take the better periods.
The spectators' acceptance decreased amid frequent holding, with Parker going down various instances during close exchanges.
The underdog closed well, but multiple periods were difficult to score. However, former world champion Carl Frampton - working with Dazn - had it strongly leaning for Parker, scoring for Buatsi just one round.
Buatsi moves on, but with the likes of hard hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - on this evidence - still seems difficult.
Hatton Memorial Inspires Manchester Derby Battle
In the secondary fight, Arthur defeated Rea by divided decision in a excellent Manchester vs Manchester fight to win the European light-heavyweight belt.
The venue became quiet for a profoundly moving homage ahead of the contest as ten bells rang in memory of local hero Hatton, who succumbed at age 46 in recently.
It was the initial significant broadcast match card in the location since the passing of Hatton. As the concluding sound faded, the silence transitioned to a chant of "there's only one Hatton".
The fighting during the bout reflected the emotion. Arthur was floored by a left hook squarely on the jaw in the initial stage, rising shakily to his feet on the eight count.
But the red-colored shorts of Arthur soon came forward again. On the opposite side, the opponent - in competitive blue - was marked up early, heavy swelling forming under his orbital area as the pair exchanged punishing blows.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with effective uppercuts as the action seldom decreased over twelve rounds.
Arthur barely secured the decision with official scores of 114-114, narrow lead and 115-112, but the two athletes were determined and courageous, exactly what their hero the legend embodied.
