The 61-year-old trainer is of the opinion that Tito Vilanova has a difficult task on his hands to replicate the successes and glory of the outgoing Camp Nou boss
The retired midfielder will step down as Blaugrana trainer at the end of the season, having won three back-to-back La Liga titles and two Champions League crowns.
Del Bosque feels that Guardiola is practically irreplaceable, and believes the coach has been a great ambassador for Spanish football.
"It will be impossible for anyone to achieve what Guardiola has achieved at Barcelona," the 61-year-old told reporters at a press conference.
"When he started coaching Barcelona I had left Real Madrid, but I have a great friendship with him through the Barcelona players.
"Pep is a person who has been a credit for Spanish football and has left a legacy. Guardiola is unique in history, he cannot be matched by anyone."
Del Bosque went on to admit that Guardiola should be a front-runner for the Spanish national coach role in the future.
"I imagine that when the RFEF have to appoint a new [Spain] coach, they will look for the best and Guardiola is among the best," he added.
"But we have a large group of Spanish coaches and there are many skilled people that could lead the team."
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