WBO lightweight champion Ricky Burns told Ringside that fighting IBF title-holder Miguel Vazquez will be trickier than taking on Adrien Broner.
Burns, 29, said facing Vazquez in London on March 16 will be the toughest fight of his career to date and defending his title will be a "big ask".
The Scot also denied that he took the fight to avoid meeting WBC lightweight champion Adrien Broner, who takes on Welshman Gavin Rees this Saturday and, moreover, insisted that he would love a crack at the American and stressed that Broner won't have an easy ride against Rees.
"There's been talk about that fight for the last couple of years, obviously down at featherweight," he said.
"I had the opportunity to fight him in February but Gavin Rees has got that shot now. A lot of people have been saying that Gavin's not got a chance.
"I've actually sparred with Gavin a few times. He's a really nice guy and he's very underestimated. He's got a high work rate and he likes to come out and put it on you, but he's got a good boxing brain on him as well. This could be a tricky fight than people - and Adrien Broner - think."
He added: "People say that I've been avoiding Adrien Broner - that's not the case. The only reason I didn't take it was due to the lack of time I had to prepare.
"If the date was moved, I wouldn't have a problem fighting Adrien Broner. Going over to America is something I've always wanted to do - I don't mind travelling because a boxing ring is a boxing ring, but I believe Miguel Vazquez, style-wise, could be a trickier fight than Adrien Broner.
"This is going to be the biggest and toughest fight of my career. I cannot look beyond this fight.
"There are two World titles on the line and he's not the IBF champion for nothing - he's had five or six defences so he is a very, very good fighter. I know that this is a big ask and it's going to be a tough, tough fight.
"He's only ever lost to two fighters who were at the top of their game, Saul Alvarez and Timothy Bradley, so I know it's a big ask but these are the fights that are going to bring out the best in me and these are the ones that I've always wanted."