Six-goal Monaco storm into French Cup semis
Monaco's French forward Emmanuel Riviere (2nd L) celebrates with teammates after scoring during the French Cup football match between AS Monaco and RC Lens, on March 26, 2014, at the Louis II stadium in Monaco - by Valery Hache
Monaco boss Claudio Ranieri, whose side are 10 points behind runaway leaders Paris Saint-Germain in the Ligue 1 title race, made six changes from the team's last outing against Lille at the weekend.
But the changes made little difference to the outcome against a Lens team who are second in Ligue 2 and seeking a return to the top flight.
Argentine winger Lucas Ocampos scored Monaco's opener after 17 minutes and added his second of the night in the 69th minute.
Dimitar Berbatov, Emmanuel Riviere, Fabinho and Geoffrey Kondogbia were also on target for Monaco.
In the semi-finals, to be played on April 15 and 16, Monaco will face Guingamp while second-division Angers will meet either Rennes or Lille who clash in Thursday's remaining quarter-final.
Guingamp reached the last-four with a 2-0 win over Cannes, who had put out Saint-Etienne and Montpellier in earlier rounds, with Mustapha Yatabare scoring two late second-half goals.
Amateur side Cannes' hopes of an upset were dented eight minutes from the end of the first half when Lucas Roubah was sent off for a crunching tackle on Claudio Beauvue.
On Tuesday, Angers ended amateurs Moulins' hopes with a 4-2 penalty shoot-out win.