But according to the Sun, the Blues looked to have been pipped to Mario’s signature by Inter Milan.
The Serie A giants, the report claims, have seen a £29m bid accepted by Sporting.
It is thought the player has agreed personal terms and will sign a five-year deal.
The report also suggests Mario, who could sign for Inter in the coming hours, will triple his wages at the San Siro, and will earn around £29,000 a week.
Mario played a starring role for Portugal at Euro 2016, helping them beat France in the final last Sunday.