Tottenham are looking to sign the Portuguese international Adrien Silva this summer.
The 28-year-old has been a key player for club and country over the last two seasons and the Londoners want him to aid their title challenge next season.
According to Portuguese outlet A Bola, Tottenham submitted an initial offer of £17.3m for the Sporting captain. However, the opening offer has been rejected and the Londoners have returned with an improved offer of around £26m.
The report adds that Sporting might be willing to sell their key star for around £30m this summer.