Lens warm up for Arsenal trip with comfortable victory at Clermont
Elye Wahi's early strike got Lens up and running before Adrien Thomasson and Wesley Said's second-half strikes completed the job in a match in which both teams were reduced to 10 men.
Lens beat Arsenal at home in October but might need another shock result next week to keep their first Champions League campaign since 2002 alive.
The French club sit third in Group B, behind PSV Eindhoven on head-to-head record and four points adrift of leaders Arsenal.
"The level that awaits us on Wednesday is that of a big mountain stage, a beyond category climb," said Lens coach Franck Haise, using cycling as a comparison.
"We will have to rise to that level. We have done it once. We will see if we are able to do it twice."
Saturday's win lifted sixth-placed Lens to within one point of the top four as last season's runners-up continue to improve after a poor start this term.
Later on Saturday, Marseille's winless run stretched to four league matches after a 1-1 draw at Strasbourg.
The southern giants fell behind early on as Emanuel Emegha put the home team ahead, although Jonathan Clauss levelled before the half-hour mark.
But Gennaro Gattuso's men could not find a winner and sit ninth in the table, 16 points behind leaders Paris Saint-Germain who thumped Monaco 5-2 on Friday.
