Reijnen, 39, was originally due to join Slot when the Liverpool manager left Feyenoord in 2024. The move fell through due to work permit complications — he did not yet hold the coaching diplomas required to work in English football. He instead stayed at Rotterdam, where he now works as an assistant to Robin van Persie with a specific focus on set-pieces.
The Liverpool Echo understands Reijnen could become a genuine option for Slot once those qualifications are secured. Dutch journalist Valentijn Driessen, speaking on Vandaag Inside, reported that a move is expected to follow completion of his diploma, with Dutch outlet 1908.nl describing him as potentially on the verge of a switch to Merseyside.
The timing is significant. Assistant coach Giovanni van Bronckhorst is heavily linked with a return to Feyenoord in a sporting director capacity, which would leave a prominent vacancy in Slot's backroom.
Reijnen is seen as the natural candidate to fill it. Former assistant John Heitinga, who left for Ajax last summer before a brief spell at Tottenham ended in February, has also been mentioned as a possible returnee.
Reijnen's set-piece record at Feyenoord is a specific selling point. The Dutch club have scored 11 goals from set-pieces this season and conceded just four — a contrast to Liverpool's record of 15 scored and 16 conceded across the same period.
Slot has been without a dedicated set-piece coach since Aaron Briggs left late last year. The responsibility has been shared across the backroom staff, and the gap Reijnen would fill is a concrete and well-defined one.