British light heavyweight Joshua Buatsi secured a victory yet unimpressive debut to his career under recent management with a decision win over Parker in Manchester.
The Olympic bronze medallist's activity level appeared to earn him a split decision in a tight ten-round fight at the boxing arena.
But Parker found success, connecting with powerful clean blows in a fight where the techniques didn't complement each other, with frequent clinching disrupting the action.
Two judges judged it 96-94 to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my finest performance but how do champions respond? They prevail," Buatsi stated in the ring as he was faced negative reactions from the crowd.
The British fighter got back to winning after his initial pro loss - an epic battle with Callum Smith in last winter - to earn a 20th pro success.
Some ringside observers believed Parker, 31, should have been awarded the win but the Derbyshire fighter endured the second setback of his 28-bout career.
The Champion Secures Victory in Dull Match
The fighter's advancement has stalled in recent times through management issues and considerable time of inactivity.
Once tipped as the rising talent of British boxing, he now finds himself trying to achieve expectations - perhaps in what feels like a last chance - under fresh management.
He started carefully, with the two boxers ready to overcommit in a calculated early stages.
The challenger, whose only previous defeat came at super-middleweight against John Ryder in 2022 after damaging his hand in the contest, was competing in only his second fight at the higher weight class.
By the fight's midpoint, Parker had made it competitive, causing problems for Buatsi, who worked behind a solid defense to narrowly win the cleaner rounds.
The spectators' acceptance diminished amid regular grabbing, with Parker going down several times during close exchanges.
The underdog ended stronger, but several stanzas were hard to judge. However, previous titleholder Carl Frampton - commentating on Dazn - had it strongly leaning for the challenger, awarding Buatsi just a single round.
Buatsi moves on, but with the caliber of power puncher Benavidez, and Russian champion Bivol ruling the division, the road to world glory - based on this performance - still appears challenging.
Ricky Hatton Tribute Inspires All-Manchester Contest
In the secondary fight, Lyndon Arthur overcame Bradley Rea by divided decision in a terrific local rivalry contest to win the European light heavyweight championship.
The stadium grew hushed for a extremely emotional tribute ahead of the contest as ten bells sounded in honor of the city's native Hatton, who passed away 46 years old in September.
It was the first major televised match card in the location since Hatton's passing. As the last bell ended, the silence became a chant of "there's just one Hatton".
The competition during the bout reflected the emotion. The eventual winner was knocked down by a powerful punch directly to the face in the early round, standing uncertainly to his footing on the count of eight.
But the traditional red shorts of the fighter soon advanced again. On the opposite side, Rea - in opposing blue - was damaged soon, significant bruising appearing under his orbital area as the pair traded powerful shots.
Rea, twenty-seven, delivered effective strikes but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace hardly diminished over 12 rounds.
The victor barely secured the decision with official scores of draw, close margin and clearer margin, but each competitor were relentless and brave, exactly what their idol the legend stood for.
