Gündoğan recently announced that he will not extend his current contract with Dortmund which expires in June 2016.
The 24-year-old also confirmed that he is in talks with Barcelona. Gündoğan went onto state that no decision has been made regarding his future.
“Rarely have I witnessed a player with the intelligence and ability which Gündoğan possesses,” Riedle told Goal Germany.
“So I’m sure he can be a success at Barca. For me he is like a ‘modern Xavi’ that is able to regulate and dictate the rhythm of the game.
“In this area, he is one of the The best in the world.”
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Riedle is a retired Germany international striker who was nicknamed “Air” due to his incredible jumping ability and timing skills for headers.
The 49-year-old made 207 Bundesliga appearances over the course of eight seasons, he also played for Lazio and Liverpool.
Gündoğan has five assists and three goals in 32 appearances for Dortmund despite spending much of the season out injured and is almost certain to leave the Bundesliga giants over the summer.