Hernandez had a surprisingly easy time in a 6-3, 6-2 win over Monfils and moved into the quarterfinals against fifth-seeded Julien Benneteau.
Benneteau was 6-4, 6-4 winner over Pablo Cuevas in his Wednesday match.
Second-seeded Jo-Wilfried Tsonga knocked off Lamine Ouahab, 6-3, 6-2, to secure his quarterfinal slot. He will be paired against Santiago Ventura, who won this event in 2004. Ventura needed to come back for a 2-6, 6-4, 6-0 second-round win over Rainer Schuettler to advance.