Leeds United reportedly spent £500,000 on Caleb Ekuban in the summer of 2017.
Leeds United continue to be linked with Swansea City winger Daniel James.
Spanish goalkeeper Casilla joined Leeds last week from Real Madrid.
Kiko Casilla is reportedly heading to Championship table-toppers Leeds United from La Liga giants Real Madrid.
Sacko is struggling on loan from Leeds at Spanish side Las Palmas.
The Leeds United boss and Victor Orta were watching the youngsters today.
The Leeds United manager has reiterated his desire to strengthen in January.
Championship leaders Leeds United are reportedly hoping to snap up Swiss international Zuber from Bundesliga side Hoffenheim.
Hadi Sacko is on loan at Spanish second tier side Las Palmas from Championship league leaders Leeds United.
Saiz has left Leeds to join Getafe on a loan-to-buy deal, beginning in January.