Amir Khan is desperate for Gavin Rees to beat Andreas Kotelnik in Cardiff on Saturday - so he can challenge for the Welshman's WBA light-welterweight belt.
Khan is undefeated in 16 professional fights
Rees recently claimed he would give 21-year-old Khan "a pasting" if they ever met in the ring.
"I've never wanted someone to win a fight so much before," said Khan, the Commonwealth lightweight champion.
"I want to be a world champion before the end of the year, and Rees is a realistic target."
Khan, who faces Denmark's Martin Kristjansen in a WBO lightweight title eliminator at the Bolton Arena on 5 April, added: "I badly want Rees to win so I can shut him up once and for all.
Khan reckons he's Mr Big, but I'll give him a right good pasting, I'll smash him to pieces
"He's a good champion and is only one weight class higher than me, but I'll happily step up and take him on. I'll be too quick and punch too hard for him.
"He's been calling me out for a while now, and I'd love to take him on. I'll even come to Cardiff and beat him in front of his own fans.
"I'm concentrating on my fight with Martin Kristjansen next month, but Rees has got my juices flowing."
The unbeaten Rees, 27, claimed the WBA title from France's Souleymane M'baye last July but his fight against Kotelnik is only his first defence.
The Ukrainian has won 28 of his 31 fights and drew with then title-holder M'baye when the two met in Liverpool last March.
Rees said: "Kotelnik is a good fighter, and I know I'll have my work cut out to beat him.
"But I'm in the shape of my life and ready to go 12 hard rounds against anyone. I don't believe Kotelnik can beat me.
"Khan's been opening his gob a lot recently, but if he does that when he's near me I'll stick my fist straight in it.
"Khan reckons he's Mr Big, but put him in the ring with me and I'll give him a right good pasting. I really believe I'll smash him to pieces.
"After I've sent Kotelnik packing I'll be straight on the phone to our promoter Frank Warren begging him to get the Khan fight done, because I'll knock him out in six rounds."