The Ballon d'Or winner stood over the free-kick before striking into the bottom left-hand corner, away from the reach of Gremio goalkeeper Grohe.
The ball found a gap in the wall to give the Spanish giants a deserved lead and demoralise Gremio, whose first-half efforts were all in vain.
Renato Gaúcho se tá bravo?@Cristiano Ronaldo tá favorável?#RealMadrid
— Protagonistas (@oiieeee88) 16 December 2017
Real Madrid 1x0 Grêmio pic.twitter.com/5z8bLN1t0L