The Reds were prepared to sell Grujic last summer, but eventually sanctioned another loan deal and he headed to Portugal.
They allowed him to join Porto on loan and he has blossomed in Portugal under the guidance of coach Sergio Conceicao, and made 39 appearances for the club in all competitions.
Porto are keen to sign him on a permanent deal but Grujic also has suitors in Italy and Germany this summer.
The Portuguese giants are claimed to be the front runners in the chase to secure the midfielder’s signature.
Porto will look to step up on their efforts to secure a deal with Liverpool for Grujic as soon as possible.
With several clubs interested in the Serbian, the Reds are confident that they will earn the £15m they want from his departure.
It could mean a hefty profit on a player they signed from Red Star Belgrade for a fee of £5.1m.
Grujic has been on several loan spells but failed to impress Jurgen Klopp enough to get regular game time at Anfield.