Robert McCracken, the trainer for IBF, IBO, WBA heavyweight champion Anthony Joshua (20-0, 20 KOs), wants his boxer to be lighter for the upcoming showdown with WBO champion Joseph Parker (24-0, 18 KOs).
The fight is expected to be announced in the coming days for March 31 at Principality Stadium in Cardiff, Wales.
McCracken was not happy with Joshua coming in at a career-high 254-pounds for his October bout with Carlos Takam.
Joshua, 28 years old, stopped Takam in the tenth round, but he tired in the later rounds and didn't perform as well as he did in previous fights.
McCracken is not underestimating the threat of Parker and wants his fighter to be at his very best.
"He's a bit lighter [than he was in his last fight] at the minute, he's probably eased off a bit on the conditioning side of things strength wise," McCracken told BBC Radio 5 live's boxing podcast.
"We do 12 weeks for his fights so I can give him some days off during the camp here and there as we go. He's done four weeks with me in London before Christmas - boxing and cardio - so he's in good shape, sharper and a little bit leaner than he was of late."
The contest with Parker is what Joshua wants to be the start of a unification conquest in 2018.
Parker, who also holds a win over Takam, fought back in September when he traveled over to Manchester to secure a decision win over undefeated mandatory challenger Hughie Fury. He feels very confident in his ability to knock Joshua out.
The winner of Joshua vs. Parker will be in line to unify with WBC champion Deontay Wilder in the later part of the year. Wilder has to take care of his own business on March 3rd, when he defends the belt against dangerous Cuban puncher Luis Ortiz at the Barclays Center in Brooklyn, New York.