But Cox said the Crawley Town striker, who scored four goals in 10 games on loan with Stags back in 2008, was one of a number of players he is chasing and he is hopeful of signing someone today or tomorrow.
Cox said: “I spent a day yesterday talking to representatives of players and I would like to think we are very, very close. Saying that, until paperwork is signed, sealed and delivered you can be a million miles away.
“But talks were good and I am very hopeful a deal can be done within the next 24 hours.
“I think that would give the club and the players a massive boost.”
On one potential deal, he said: “Everything was fine with the player, but I have go to be respectful with all players and their parent clubs. Until someone actually signs on the dotted line, I have got to take it as it’s not happening.
“But, from talks yesterday, things are looking very promising.”
On Sinclair, he added: “Emile is one of the shortlist I dew up for the chairman. I have spoken to his representative and a number of other representatives, but he is one I would like to bring in if he is available.”
Cox said it was possible he may be able to bring two strikers in, but added: “That is an option, but we mustn’t try to run before we can walk.
“We have our targets. They are players we have been looking at for a while and we have been patient. Sometimes that is the key in these deals. But there are so many facets to signing a player.
“It is part of the job that I enjoy – the business side of it.
“You can’t just be a good coach or manager. You have to be a businessman as well, especially in the Football League when you are dealing with quite large sums of money, but the chairman has been supportive throughout.
“It can all hinge on just one part of the contract. You can lose a deal through that.”