Lining up alongside free-kick maestro Joao Moutinho, Monaco midfielder Thomas Lemar caught Remy Vercoutre off guard, firing a 30-yard free-kick off the post and in to give the visitors a 1-0 advantage.
Caen's Julien Feret equalised from the penalty spot eight minutes later before Alaeddine Yahia's own goal gave the principality side the lead again.
