Joseph Parker had secret double elbow surgery in December to improve his performance, the Herald can reveal.
The procedure has helped his movement and power significantly; Parker and his team believe it will be a game-changer for his fight against Anthony Joshua.
The Parker camp have been desperate to keep his operation under wraps.
Firstly for fear of upsetting the delicate and lucrative negotiations with Joshua and his promoter Eddie Hearn late last year, and secondly because the New Zealand heavyweight was eager to use it as a piece of mental warfare before the world title unification bout in Cardiff on April 1.
Parker and his promoter David Higgins will go into detail regarding the reasons for the surgery in Auckland, and the many benefits he has received from it, at a press conference in London late on Friday night.
Duco Events have given no details but have promised a revealing video at the press briefing, and that it will be very newsworthy.
Parker had complained of issues with his left elbow over the past few years, and it had apparently got to the point where he couldn't throw his trademark lightning double jab without extreme discomfort.
He remained stoic – and amazingly discrete (as have his team) - but apparently he would finish sparring sessions and fights in real pain. It is believed the surgery on his left elbow went so well he was determined to get his other done too.
It is significant, too, that Parker, 26, has knocked out only two of his last six opponents, and that he has looked flat in several bouts, in particular during his last two against Hughie Fury last September and Razvan Cojanu last May.
While going 12 rounds against Carlos Takam, and Andy Ruiz Jr – for the WBO world title – plus Cojanu and Fury, proved Parker can easily go the distance (something knockout artist Joshua is yet to do), Parker was desperate to stop Fury and his disappointment, before the relief of the announcement of the majority decision, was clear.
It is believed the elbow trouble could have contributed slightly to the weight gains Parker made before this camp. He has also recently made mention of factors that have prevented him from showing his true potential without explaining what they were.
The true value and quality of his recent camp in Las Vegas will only be known in hindsight following his fight at the Principality Stadium in front of a record crowd of 80,000 people and TV audience of millions, but Parker and his trainer Kevin Barry have said it has been the best of his career.
Parker looks very trim, particularly around his face, after arriving in London, and is apparently on track to tip the scales at the 107kg or 108kg he is targeting. He was 111.1kg for his last fight against Fury, a fight in which he landed several right hands on the Englishman's chin without appearing to make too much of an impact.
The speed, and the one-punch knockout power, is apparently back now, and that is why he and Barry have arrived in London supremely confident of pulling off one of the great upsets in the sport.
Hearn has, over the past few months, wondered aloud why Parker, the WBO world champion, and his team were so confident of pulling off a victory against Joshua, the holder of the IBF, IBO and WBA belts and a man who has won all of his 20 professional fights early.
The surgery, and the freedom and power it has brought back to Parker's punches is the reason why.
Boxing writer Patrick McKendry will be in London and Cardiff to cover the Joshua v Parker fight for NZME. Get The New Zealand Herald, check nzherald.co.nz regularly for updates and listen to his informed view from London and Cardiff Radio Sport and Newstalk ZB for on-the-ground reports.