"In March we're going to do trials with Dortmund and that will determine what I do with that career, which way it goes," he told the Daily Express

"If they say I'm good, and that I need a bit of training, I'll do it.

"It makes me nervous. I don't get nervous but this is different, this is football now. It'll take time to adjust but once I play a few times I'll get used to it. It was the same when I started track and field.

"I was nervous for a while until I started getting used to the crowd, people and everyone around and it falls into place.

"One of my biggest dreams is to sign for Manchester United. If Dortmund say I'm good enough, I'll crack on and train hard.

"I've spoken to Alex Ferguson and I told him he needs to put in a good word. He told me if I get fit and ready, he will see what he can do."

He added: " watch a lot of football, I understand it, I play it.

"With training, I could be good. Me and [Paul] Pogba talk a lot. I watch and ask him a lot of questions.

"I want to play but it has to be in the top league. I'm not content to be average.

"I strive to be the best and if I get a chance to play for a team like Manchester United it will be a massive deal."

The eight-time Olympic gold medallist retired from athletics last August after the World Championships in London.