Anthony Joshua has urged Deontay Wilder not to "rob the fans" and agree to an undisputed world heavyweight title fight.
Joshua wants to face his fellow champion in a battle for every major belt if he comes through Saturday night's defence of the IBF, WBA and WBO gold against Andy Ruiz Jr, live on Sky Sports Box Office.
He has now appealed to WBC titleholder Wilder to reverse his decision to next fight Luis Ortiz. Joshua said: "Whatever he is doing with his career, good luck to him. However, I am a fan of the sport. I have tried to challenge all the best fighters out there, bar one or two. I am reaching out to them.
"Let's not rob the fans of a good fight. I am a fan of this sport and I feel like I'm robbing myself of a good fight.
"Good luck to whatever he is doing. But if he wants to come and see us - because he hasn't announced a date or a venue - then we can have a conversation."
Joshua and Wilder are unbeaten in a combined 64 fights, 62 of which have been won by knockout, and own every heavyweight belt between them. Wilder stopped challenger Dominic Breazeale inside a round earlier this month and Joshua, this week, implored his rival to meet for "face to face" talks to agree to a much-anticipated fight.
Wilder, instead, revealed plans to rematch Ortiz in his next outing.
"Credibility in the division comes from who is calling who out, rather than who is fighting! I don't need to be negative towards him," Joshua said.
"Even though I am a professional I still think: 'if I get past this job, what else is out there?'
"I won't lie and deny it. I know how important this fight is. But I want what's next. I want it all.
"I have done the hard yards and my hard graft. I have done training camps when I felt ill, gone into fights when I didn't feel good. I want to challenge the best."
Asked who he might fight if Wilder doesn't agree, Joshua said: "There are other challenges out there like Kubrat Pulev, Oleksandr Usyk, Michael Hunter, Tyson Fury, Dillian Whyte. If it's not Wilder I will have to go somewhere else.
"What can I do? Hopefully he comes to his senses and comes to see us."
Joshua must first deal with the challenge of Ruiz Jr, who has lost just once in 33 fights, when he faced Joseph Parker in 2016.
"Saturday night is about positive energy," Joshua said. "I can add my 11 years of boxing into one, and move into the next phase. I am a dominant force.
"Before, I was boxing under pressure. I didn't want to lose or get hit. I was scared of losing, because of everything we have worked for.
"Now I will go in there, and show everyone how good I am.
"Fighting Andy is just as dangerous as fighting Wilder or Fury. They each possess their own skills. It is a banana skin for me.
"Andy will give me a good fight and cause problems. It's down to me, as the champion, to think smart and box clever.
"Out-skill, out-strength and out-muscle Andy Ruiz Jr."
Watch Anthony Joshua vs Andy Ruiz Jr on Saturday, live on Sky Sports Box Office, from 10pm. Book it via your Sky remote or book it online here. Even if you aren't a Sky TV subscriber you can book and watch it here.