Joseph Blatter has offered his help to newly elected FIFA president Gianni Infantino but has told him miracles will be expected and friends "become rare."
"I congratulate you, but remember however that this position you wanted will not be easy. Miracles will be expected," Blatter wrote in an open letter published in French newspaper, Journal du Dimanche.
Blatter's 18-year reign as head of football's world governing body officially ended with Infantino's election Friday.
Now banned from football for six years, Blatter said the reforms passed at FIFA's extraordinary congress in Zurich will help fellow Swiss Infantino in his bid to restore credibility at the scandal-hit body.
"The miracles will be helped by the vote overwhelmingly taken for the reforms which I had also started," 79-year-old Blatter said.
"If by chance, you want an opinion or advice, do not hesitate. For now, stay calm. You have two months to implement the decisions taken."
Infantino should be "vigilant," Blatter added.
"While everyone supports you and tells you nice words, know that once you are the president, friends become rare."