UK light-heavyweight Joshua Buatsi earned a win yet disappointing start to his career under recent management with a decision win over Parker in Manchester.
The Olympic medal winner's punch output seemingly secured him a split decision in a tight ten-round contest at the Co-op Live Arena.
But Parker found success, landing some telling clean blows in a match where the techniques never quite clicked, with frequent clinching disrupting the contest.
Two judges judged it 96-94 in favor to the winner, with the final judge a even score.
"It wasn't my best showing but what do champions do? They prevail," Buatsi commented in the ringside as he was met by negative reactions from the audience.
The British fighter returned to winning ways after his initial pro loss - an thrilling contest with his previous opponent in February - to secure a 20th career victory.
Several boxing experts thought the challenger, 31, should have been awarded the decision but the British boxer experienced the second loss of his 28-bout career.
The Champion Earns Victory in Dull Encounter
Buatsi's progress has plateaued in recent years through management issues and extended periods of inactivity.
Previously predicted as the future of UK boxing, he now is positioned trying to achieve expectations - perhaps in what seems like a ultimate opportunity - under new promotional backing.
He began cautiously, with the two boxers willing to be aggressive in a cagey initial rounds.
Parker, whose single earlier setback came at the lower weight class against his former opponent in two years ago after damaging his hand mid-fight, was competing in only his second bout at the higher weight class.
By the middle rounds, Parker had made it competitive, making life awkward for Buatsi, who worked behind a tight guard to barely take the cleaner stanzas.
The spectators' acceptance diminished because of frequent holding, with the challenger falling to the floor several times during close exchanges.
The underdog ended stronger, but several stanzas were difficult to score. Although, ex-champion the boxing analyst - commentating on the broadcast network - had it particularly wide for Parker, giving Buatsi just only one stanza.
Buatsi moves on, but with the caliber of heavy hitter Benavidez, and Eastern European fighter Bivol dominating the weight class, the journey to titles - based on this performance - still appears challenging.
Hatton Tribute Inspires All-Manchester Fight
In the supporting bout, Arthur defeated Bradley Rea by divided decision in a outstanding all-Manchester contest to win the European light-heavyweight championship.
The venue fell silent for a extremely emotional tribute before the fight as a bell ceremony rang in remembrance of the city's native Ricky Hatton, who succumbed at age 46 in recently.
It was the initial significant broadcast boxing event in the location since Hatton's passing. As the concluding sound disappeared, the stillness became a chant of "there's only one Hatton".
The competition inside the ropes matched the emotion. Arthur was floored by a powerful punch squarely on the face in the initial stage, standing uncertainly to his footing on the eight count.
But the Manchester United-red equipment of Arthur soon came forward again. From the other corner, Rea - in rival City blue - was injured early, significant bruising forming under his face as the duo landed punishing blows.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with powerful upward punches as the action rarely dropped over twelve rounds.
Arthur narrowly won the decision with judges scorecards of draw, close margin and clearer margin, but both fighters were persistent and courageous, exactly what their idol Hatton embodied.
