Mbappe has scored three times for his country at this summer's competition, and the 19-year-old has now received more praise from his international teammate Giroud.
"In recent football we've never seen that before and he can still improve again and again. He's like a rough diamond and we need to keep polishing it. He's got a big future ahead of him," Giroud told reporters.
Mbappe entered this year's World Cup off the back of scoring 21 times in 46 appearances for Paris Saint-Germain last season.