UK light-heavyweight Joshua Buatsi earned a win yet underwhelming start to his career under recent management with a decision win over Parker in the Manchester arena.
The Olympic medal winner's work rate appeared to earn him a split decision in a competitive ten-round fight at the Co-op Live Arena.
But the challenger found success, delivering effective single shots in a fight where the styles never quite clicked, with frequent clinching marring the fight.
Two judges judged it 96-94 in favor to Buatsi, with the third a even score.
"It wasn't my finest display but what defines champions? They succeed," the victor commented in the arena as he was met by boos from the spectators.
The British fighter bounced back after his maiden career setback - an epic battle with Callum Smith in last winter - to secure a twentieth professional win.
Some ringside observers felt the challenger, 31, should have been awarded the victory but the British boxer experienced the second loss of his 28-match career.
Buatsi Secures Win in Uneventful Match
His career development has slowed in recent years through management issues and long spells of inactivity.
Earlier forecast as the future of the British fight scene, he now stands trying to realize his potential - perhaps in what feels like a final roll of the dice - under recent support.
He began cautiously, with the two boxers willing to take risks in a calculated early stages.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after breaking his hand in the contest, was participating in his second bout at light heavyweight.
By the halfway stage, Parker had stayed in contention, creating difficulties for Buatsi, who utilized a protective stance to narrowly win the better rounds.
The audience's tolerance decreased because of regular grabbing, with the challenger slipping to the canvas several times during close exchanges.
The underdog closed well, but several stanzas were challenging to assess. Nevertheless, former world champion the boxing analyst - commentating on the broadcast network - had it particularly wide for the challenger, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the path to championship success - judging by this showing - still looks steep.
Ricky Hatton Tribute Inspires Local Rivalry Contest
In the co-main event, Lyndon Arthur beat Bradley Rea by split-decision in a terrific local rivalry battle to win the European light heavyweight belt.
The venue grew hushed for a profoundly moving memorial ahead of the contest as a bell ceremony tolled in memory of local hero Ricky Hatton, who passed away at age 46 in September.
It was the initial significant broadcast fight night in the urban center since the passing of Hatton. As the last bell disappeared, the silence gave way to a chant of "only one Ricky Hatton".
The fighting within the ring reflected the sentiment. Arthur was floored by a left hook directly to the jaw in the early round, getting up unsteadily to his feet on the referee's count.
But the red-colored attire of Arthur soon came forward again. On the opposite side, Rea - in competitive blue - was marked up quickly, significant bruising forming under his orbital area as the pair traded powerful shots.
The challenger, twenty-seven, connected with strong blows but Arthur, 34, matched the intensity with powerful upward punches as the pace hardly diminished over twelve rounds.
The victor barely secured the verdict with official scores of 114-114, close margin and clearer margin, but the two athletes were persistent and brave, exactly what their hero Hatton embodied.
