Hernandez, 27, reportedly gave his 'green light' to a proposed switch to the former internal Milan manager Simeone Inzaghi's al-Hilal side.
AC Milan has now increased their pursuit of a replacement and prioritizing a movement for Arsenal left back Oleksandr Zinchenko, 28.
Mikel Arteta's side would be willing to have the Ukrainian leave this summer if they receive an offer of approximately € 20 million (£ 17 million/$ 23 million).
However, Zinchenko's wage would be a bottleneck, limited with AC Milan after not qualifying for the Champions League of next season.