Belgium international of Ghanaian descent
The 27-year-old forward beat Fabio Coentrao and Nacho before he blasted the ball on the blind side of Keylor Navas.
Earlier in the game Wales forward Gareth Bale recorded the fastest-ever goal in Champions League history to put Real Madrid ahead after 57 seconds, before assisting Karim Benzema to double their lead.
But goals by Vadis Odjidja-Ofoe and Miroslav Radovic drew Warsaw level, before the Polish side took the lead through a superb Thibault Moulin strike.
The celebrations were short-lived though, with Madrid, on Zinedine Zidane's 100th match in charge, cancelling out Warsaw's lead only two minutes later through former Inter midfielder Mateo Kovacic.