British light heavyweight Joshua Buatsi earned a win yet unimpressive beginning to his career under new promoters 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 tight 10-round contest at the Co-op Live Arena.
But Parker had his moments, landing some telling clean blows in a contest where the styles didn't complement each other, with frequent clinching disrupting the fight.
Two judges had it 96-94 for to the winner, with the third a even score.
"It wasn't my best performance but how do champions respond? They succeed," Buatsi commented in the ring as he was faced boos from the crowd.
The Londoner bounced back after his initial pro loss - an thrilling contest with Callum Smith in February - to earn a twentieth professional win.
Some ringside observers believed the challenger, 31, deserved the decision but the British boxer suffered the second loss of his 28-match professional journey.
The Champion Earns Victory in Slow Encounter
Buatsi's progress has plateaued in recent times through promotional disputes and extended periods of inactivity.
Once tipped as the next star of the British fight scene, he now stands trying to achieve expectations - possibly in what seems like a last chance - under new promotional backing.
He began cautiously, with both competitors willing to take risks in a cagey initial rounds.
The challenger, whose sole prior loss came at the lower weight class against his former opponent in 2022 after damaging his hand during the bout, was competing in only his second fight at the higher weight class.
By the halfway stage, the underdog had made it competitive, creating difficulties for the favorite, who utilized a tight guard to edge the more effective stanzas.
The spectators' acceptance decreased because of regular grabbing, with the challenger falling to the floor multiple occasions during close exchanges.
Parker closed well, but multiple periods were challenging to assess. However, ex-champion the boxing analyst - commentating on the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just a single round.
Buatsi moves on, but with the presence of power puncher Benavidez, and Russian star Dmitry Bivol ruling the division, the path to championship success - judging by this showing - still appears challenging.
Hatton Tribute Fuels Local Rivalry Battle
In the supporting bout, Lyndon Arthur defeated Bradley Rea by split-decision in a terrific local rivalry fight to win the European light heavyweight title.
The venue grew hushed for a profoundly moving homage prior to the bout as 10 bells rang in honor of local hero Ricky Hatton, who died at age 46 in September.
It was the premier televised fight night in the city since the passing of Hatton. As the final chime ended, the stillness gave way to a shout of "there's just one Ricky Hatton".
The fighting within the ring equaled the emotion. The eventual winner was knocked down by a left hook squarely on the chin in the second round, standing uncertainly to his feet on the referee's count.
But the Manchester United-red equipment of Arthur soon came forward again. From the other corner, the opponent - in competitive blue - was damaged soon, heavy swelling developing under his face as the fighters traded powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, matched the intensity with effective uppercuts as the action rarely dropped over 12 rounds.
The victor edged the verdict with scoring tallies of even score, 115-113 and clearer margin, but the two athletes were determined and full of heart, exactly what their inspiration the legend embodied.
