There have been question marks over if it would be possible considering Monday, January 2, is a public holiday and the need for the FA to rubber stamp the deal before he has the right to feature.
But it appears it will be possible for Jurgen Klopp to name Gakpo in his squad should all the formalities be completed as expected ahead of the transfer window opening on January 1.
Gakpo is to undergo his medical imminently ahead of his £37 million move from PSV, but just because he will be eligible at Brentford does not mean he will take any part.
It came naturally to Diaz to slot into the team and the hope will be Gakpo can enjoy a similar transition at Anfield.
As for his Champions League eligibility, clubs can register a maximum of three new players after the January window, irrespective of if they have played for another club in the competition this season.
There will need to be a reshuffle of the squad to cater for a non-homegrown player but injuries could dictate who is in and out.