UK light-heavyweight Joshua Buatsi made a winning yet underwhelming start to life under new promoters with a points victory over Parker in Manchester.
The Olympic medal winner's work rate seemingly secured him a majority decision in a close ten-round contest at the boxing arena.
But the challenger had his moments, delivering effective single shots in a match where the styles never quite clicked, with frequent clinching marring the action.
The scoring judges judged it 96-94 in favor to the winner, with the third a 95-95.
"It wasn't my best showing but how do champions respond? They succeed," the victor commented in the ring as he was met by boos from the audience.
The Londoner returned to winning ways after his first professional defeat - an thrilling contest with his previous opponent in last winter - to earn a 20th career victory.
Various analysts believed Parker, thirty-one, merited the victory but the Derbyshire fighter experienced the second setback of his 28-bout professional journey.
Buatsi Secures Win in Dull Encounter
His career development has stalled in recent times through management issues and long spells of inactivity.
Previously predicted as the rising talent of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what feels like a last chance - under new promotional backing.
He opened tentatively, with neither fighter prepared to take risks in a cagey opening few rounds.
The challenger, whose only previous defeat came at the lower weight class against his former opponent in 2022 after breaking his hand mid-fight, was competing in only his second fight at light heavyweight.
By the fight's midpoint, Parker had made it competitive, making life awkward for Buatsi, who worked behind a tight guard to narrowly win the cleaner stanzas.
The crowd's patience wore thin during constant clinching, with Parker slipping to the canvas several times during clinches.
Parker ended stronger, but many rounds were difficult to score. However, former world champion Carl Frampton - commentating on Dazn - had it strongly leaning for Parker, scoring for Buatsi just a single round.
Buatsi moves on, but with the presence of heavy hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - on this evidence - still looks steep.
Hatton Tribute Inspires Manchester Derby Fight
In the secondary fight, Lyndon Arthur defeated Bradley Rea by split-decision in a outstanding local rivalry battle to win the European light-heavyweight championship.
The venue became quiet for a profoundly moving homage ahead of the contest as 10 bells rang in honor of Manchester's own Hatton, who passed away at age 46 in recently.
It was the premier televised boxing event in the city since Hatton's passing. As the concluding sound faded, the silence gave way to a shout of "there's only one Hatton".
The action within the ring matched the feeling. Arthur was knocked down by a significant blow directly to the face in the initial stage, rising shakily to his footing on the referee's count.
But the red-colored shorts of the fighter soon advanced again. From the other corner, the opponent - in opposing blue - was marked up quickly, significant bruising appearing under his orbital area as the pair landed hard punches.
The challenger, 27, landed power punches but Arthur, thirty-four, matched the intensity with stinging uppercuts as the pace rarely dropped over twelve rounds.
The victor barely secured the verdict with official scores of even score, close margin and clearer margin, but the two athletes were determined and courageous, everything their idol the legend stood for.
