Hernandez injured his hamstring in the clash at Fulham four days before Christmas and the Spaniard was thought to be looking at a month out but the attacking midfielder takes his place on the bench along with Jamie Shackleton who also returns from a hamstring problem.
Whites head coach Marcelo Bielsa has made two changes to the Whites side that lined up in United's most recent league game at West Brom with Patrick Bamford starting in the lone striker role after Eddie Nketiah's Arsenal recall and Barry Douglas replacing Gjanni Alioski at left back as Alioski drops to the bench.
Tyler Roberts is still missing with a hamstring injury while Adam Forshaw remains out with a hip problem.
Leeds United v Sheffield Wednesday: Casilla, Ayling, White, Cooper, Douglas, Phillips, Klich, Dallas, Harrison, Costa, Bamford. Subs: Meslier, Casey, Alioski, Berardi, Shackleton, Stevens, Hernandez.
Sheffield Wednesday: Dawson; Urhoghide, Iorfa, Borner, Fox; Murphy, Lee, Luongo, Bannan, Reach; Winnall. Subs: Wildsmith, Rhodes, Harris, Pelupessy, Nuhiu, Hutchinson, Hughes.
Referee: Oliver Langford.