A "drained" Jeff Horn is confident he can still produce the goods against German Rico Mueller on Friday after dropping upwards of 4kg [8.8-pounds] to make weight for the biggest fight of his life.

Australian boxing's most exciting prospect takes on Mueller at Brisbane's Sleeman Sports Complex in Brisbane in a welterweight clash that will have worldwide ramifications.

Victory will most likely take Horn to the No.2 ranking in the IBF and set up a bout with rising American star Errol Spence Jr for the soon-to-be-vacated world welterweight championship.

There is also a chance the 28-year-old could face the winner of either Manny Pacquiao or Jessie Vargas, who fight for the WBO welterweight belt on November 5.

Horn had a manic few days leading up to Thursday afternoon's weigh in, using just about every trick in the book - including hot baths and 'sauna suits' - to ensure he cleared the 66.7kg [147] limit after tipping the scales at 70kg [154] on Wednesday morning.

He did so with nearly half a kilo to spare, but both fighters will be required to weigh in again on the morning of the bout, in accordance with IBF regulations, and cannot exceed 71.7kg.

Horn admits he's hurting but after overcoming a serious throat injury to beat American veteran Randall Bailey earlier this year, nothing is going to stand in his way.

"I'll get the job done," Horn said. "I had the throat injury in my last fight, had to get over that mental battle with that.

"This is going to be nothing in comparison. I don't know how my performance will go tomorrow night but hopefully I'll still be on song."

Horn will have more than 24 hours to recover and will be counting on the support of a hometown crowd to get him through.

But the IBF's No.10-ranked fighter Mueller - who has lost only one fight in his career, a split decision six years ago, and has never been knocked down - is in the prime of his career and shapes as his toughest opponent yet.

Mueller, also 28, said his preparation has been "perfect" and believes Horn's mad scramble to make weight will be a distinct advantage.

"All I can say is everything has gone according to plan," he said. "Basically, I want to destroy his dream."