UK light heavyweight Joshua Buatsi made a winning yet unimpressive beginning to his career under recent management with a decision win over Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a judges' verdict in a competitive ten-round bout at the boxing arena.
But the challenger landed significant shots, connecting with powerful single shots in a match where the techniques never quite clicked, with frequent clinching disrupting the fight.
Two judges judged it 96-94 to the winner, with the third a 95-95.
"It wasn't my finest display but what defines champions? They prevail," Buatsi commented in the arena as he was met by boos from the audience.
The British fighter got back to winning after his initial pro loss - an thrilling contest with Callum Smith in last winter - to secure a 20th pro success.
Various analysts thought Parker, 31, deserved the decision but the contender suffered the second defeat of his 28-match career.
The Champion Claims Victory in Dull Match
His career development has stalled in recent years through promotional disputes and extended periods of inactivity.
Once tipped as the next star of UK boxing, he now is positioned trying to achieve expectations - perhaps in what appears to be 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 single earlier setback came at super-middleweight against John Ryder in two years ago after breaking his hand during the bout, was competing in only his second appearance at the higher weight class.
By the middle rounds, Parker had made it competitive, causing problems for the favorite, who utilized a protective stance to edge the more effective stanzas.
The crowd's patience diminished because of regular grabbing, with the challenger going down various instances during close exchanges.
The underdog ended stronger, but many rounds were difficult to score. Nevertheless, former world champion Carl Frampton - providing analysis for Dazn - had it particularly wide for the challenger, awarding Buatsi just one round.
Buatsi advances, but with the presence of hard hitter Benavidez, and Eastern European fighter Bivol ruling the division, the road to world glory - judging by this showing - still looks steep.
Ricky Hatton Tribute Inspires Manchester Derby Contest
In the supporting bout, Lyndon Arthur overcame Bradley Rea by close verdict in a outstanding Manchester vs Manchester battle to secure the European light-heavyweight championship.
The stadium fell silent for a extremely emotional memorial before the fight as a bell ceremony sounded in honor of Manchester's own Ricky Hatton, who died at age 46 in September.
It was the first major televised match card in the urban center since Hatton's passing. As the concluding sound ended, the silence transitioned to a shout of "there's just one Ricky Hatton".
The action inside the ropes equaled the feeling. The eventual winner was floored by a powerful punch squarely on the jaw in the early round, rising shakily to his footing on the count of eight.
But the red-colored equipment of the fighter soon came forward again. On the opposite side, Rea - in competitive blue - was injured soon, significant bruising appearing under his orbital area as the pair landed powerful shots.
Rea, twenty-seven, connected with strong blows but the champion, thirty-four, fought fire with fire with effective uppercuts as the action hardly diminished over 12 rounds.
Arthur edged the verdict with official scores of even score, 115-113 and clearer margin, but the two athletes were determined and full of heart, exactly what their hero Hatton represented.
