Jeff Horn 19-1-1 (13) has warned Michael Zerafa 26-3 (15) that his punching power has only increased since moving up from the welterweight division.

The former WBO 147-pound champion is in negotiations to face the 27-year-old Melburnian at the 4000-seat Bendigo Stadium in regional Victoria on August 31.

“I’m punching harder than ever and my body is telling me it wants to sit at the heavier weight,’’ Horn said to the Courier Mail.

Horn, 31, has seen just 96 seconds of ring time since losing his welterweight championship to talented American Terence Crawford last June, blowing out Anthony Mundine in little more than half a round last November.

Last week rising star Tim Tszyu called out Horn after his 12-round unanimous decision win of former Australian junior welterweight champion Joel Camilleri, but the Brisbane schoolteacher has warned Tszyu that he is not on his level.

“Tim says I talk like a girl because I have a high-pitched voice but he’ll find out I punch very hard if we ever fight,’’ Horn said.

“He wants to be careful what he wishes for. He’s a nice kid but he’s not at my level yet and I think he knows it. Down the track if it can be built into a big fight, I’m very confident of beating Tim comfortably.’’

Horn hasn’t given up hope of a rematch with Manny Pacquiao, who he defeated almost two years ago by unanimous decision in front of 51,000 fans at Brisbane’s Suncorp Stadium to claim the welterweight title.

The popular Filipino is scheduled to challenge WBA welterweight champion Keith Thurman at the MGM Grand in Las Vegas, Nevada on July 20.

“Pacquiao claimed he really won the fight against me in Brisbane and we’ve given him plenty of opportunities to fight me again,’’ Horn said.

“If he really wants to prove a point I’ll fight him tomorrow. I would think that his personal pride would make him want to fight me again to try to even the score.

“He’s prepared to face a lot of other big names but not me because he knows I’ll beat him again in a return fight.

“I’m very keen to see how Thurman goes against Pacquiao in July. Thurman gave me no credit at all for beating Manny so let’s see what he can do.’’