Djokovic has been in fantastic form in 2015 having won the first grand slam of the year at the Australian Open, winning three Maters Titles in a row and losing in the final of the French Open to Stan Wawrinka.
Federer feels that the Serbs red-hot form will make him tough to beat.
"I believe with the year he had and the Wimbledon last year, Novak is going to be favourite.
"He's going to be playing very well again. Anything else will be quite surprising."
The world number two did not punt his own chances at SW19, only saying that he hoped to be competitive when the event starts on June 29.
"I hope to be competitive at Wimbledon," said Federer.
"I hope I'm going to be in good shape," he added.