Celtic need results against both AC Milan and Barcelona to qualify for the last 16 of Europe's elite tournament with the Italian giants due at Parkhead a week on Tuesday, while a third-placed finish will see them drop into the other UEFA competition.
Van Dijk told the Celtic View: "It's still possible to qualify, we need two results from two games and we know we can get that.
"Our aim is still the last 16, we are not thinking about the Europa League just now.
"The group is still very tight but we have to step up our game if we are to go through.
"The AC Milan game at home is a very big one for us now, that could determine whether or not we go through, but we will also still need to go and get a result over in Barcelona."
Meanwhile, Celtic are looking to push through a deal to sign Iceland Under-21 striker Holmbert Fridjonsson after his club, Fram, confirmed they had accepted a bid for a January move.
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