UK light-heavyweight Joshua Buatsi made a winning yet underwhelming start to his career under fresh promotional backing with a unanimous decision over Parker in Manchester.
The Olympic bronze medallist's activity level seemingly secured him a split decision in a competitive ten-round contest at the Manchester venue.
But Parker had his moments, connecting with powerful individual punches in a contest where the styles never quite clicked, with constant grabbing marring the contest.
Two judges had it 96-94 in favor to Buatsi, with the final judge a 95-95.
"It wasn't my finest performance but what defines champions? They win," Buatsi said in the ringside as he was met by disapproval from the spectators.
The British fighter got back to winning after his first professional defeat - an epic battle with Callum Smith in last winter - to earn a 20th career victory.
Several boxing experts thought the challenger, 31, should have been awarded the win but the contender experienced the second defeat of his 28-fight professional journey.
The Champion Earns Triumph in Uneventful Affair
Buatsi's progress has plateaued in the past few years through management issues and considerable time of inactivity.
Once tipped as the future of UK boxing, he now stands trying to fulfil that early promise - perhaps in what appears to be a final roll of the dice - under fresh management.
He began cautiously, with the two boxers willing to overcommit in a cagey initial rounds.
The challenger, whose sole prior loss came at super middleweight against John Ryder in two years ago after suffering a hand injury mid-fight, was participating in his second appearance at light-heavyweight.
By the fight's midpoint, the underdog had kept it close, causing problems for the favorite, who utilized a protective stance to narrowly win the better stanzas.
The spectators' acceptance wore thin during constant clinching, with Parker falling to the floor various instances during grappling.
The underdog ended stronger, but several stanzas were difficult to score. Nevertheless, previous titleholder Carl Frampton - providing analysis for the broadcast network - had it significantly in favor for the challenger, awarding Buatsi just one round.
Buatsi progresses, but with the presence of power puncher David Benavidez, and Russian star Dmitry Bivol dominating the weight class, the road to world glory - on this evidence - still looks steep.
Ricky Hatton Homage Motivates Local Rivalry Battle
In the co-main event, Lyndon Arthur beat Bradley Rea by divided decision in a outstanding all-Manchester fight to secure the European light-heavyweight championship.
The stadium fell silent for a profoundly moving memorial prior to the bout as ten bells sounded in memory of the city's native Hatton, who succumbed aged 46 in last month.
It was the first major televised fight night in the city since the passing of Hatton. As the concluding sound disappeared, the silence gave way to a shout of "there's only one Ricky Hatton".
The fighting during the bout matched the sentiment. The eventual winner was sent to the canvas by a powerful punch squarely on the jaw in the second round, standing uncertainly to his position on the eight count.
But the red-colored equipment of the fighter soon pressed ahead again. Across the ring, Rea - in competitive blue - was damaged quickly, significant bruising appearing under his orbital area as the pair traded punishing blows.
Rea, twenty-seven, landed power punches but Arthur, thirty-four, matched the intensity with effective uppercuts as the pace seldom decreased over twelve rounds.
The victor narrowly won the decision with judges scorecards of 114-114, narrow lead and 115-112, but the two athletes were relentless and brave, everything their inspiration Hatton stood for.
