Since moving to Germany from Manchester City, the Englishman has evolved into one of the most devastating wingers in Europe, contributing to 33 Bundesliga goals in 2019/20 via 17 scored himself plus 16 assists.
He remains Man Utd's top transfer target this summer, but BVB are refusing to budge on their £120m valuation.
Ronaldo, meanwhile, has naturally enjoyed a stellar career and recently became only the second player in history to score 100 or more national team goals.
Guerreiro has played with both players in his career - with Sancho at Dortmund and with Ronaldo at international level with Portugal.
Although he admits Sancho has plenty of work to do to reach the heights of Ronaldo, Guerreiro believes the England international has the talent to do it.
“Jadon is still very young, but has already played an outstanding role for us in the past two years," the Portuguese told Bild.
"He has the gift of being able to make the difference - with passes, dribbles or goals.
“Cristiano is one of the best in the world and to ever be as good as him, Jadon still has a lot of work to do, a lot.
"He has everything you need, though, to be just as good as Cristiano, maybe even better someday.”
They start their 2020/21 title assault this weekend when they take on Gladbach.