Spurs chairman Daniel Levy and sporting director Damien Commoli are set to have talks with Sporting this week in a bid to beat United for the 20-year-old.
Nani recently turned down a new Sporting contract.
He told The Daily Mirror: “Sporting know my opinion about this subject. If an offer arrives which offers a good opportunity then I want to talk about it.
“Going to England is one of my options because the Premier League is one of the best leagues in the world and it will be a big challenge.
“But I have not spoken or made up my mind about any one club. I am prepared to go to England because I believe I would progress there.”