The Swiss legend, 35, made history today by downing Cilic to win his eighth Wimbledon title.
That came 14 years after his first but was marred by an injury to Cilic that saw him break down in tears on the court.
The Croat first felt the problem against Sam Querrey in the last round and revealed he kept the issue between he and his team to avoid Federer gaining a mental boost.
Cilic said: "I felt it straight after the match in the semis. I felt that the foot wasn't so good. It wasn't so bad after the match.
"We tried to take some fluid out overnight and yesterday in the morning it was worse.
Marin Cilic wanted to try keep his blistering a secret
Marin Cilic never felt comfortable during the final against Roger Federer
We kept it in the team. I was still hoping that everything is going to be good
"The doctors and physios were trying to help as much as they could. They really did the best they could, really helped a lot.
"We kept it in the team. I was still hoping that everything is going to be good."
Federer took the first set 6-3 and it was on his way to that when Cilic thinks the problem became known to his opponent.
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He said: "I think I started to give few more signals that I wasn't moving as good I think at 5-3 of the first set.
"Even today until that point, even though I was close with the score, I felt that I was just not setting up well for the balls.
Marin Cilic receives treatment for horrific blisters during Wimbledon final Sun, July 16, 2017
Express Sport brings you the best snaps as Marin Cilic receives treatment for horrific blisters during Wimbledon final
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Marin Cilic receives treatment for blisters during the Wimbledon final
"I was missing more than usual, more than that the rest of the tournament.
"I started to become a little bit more aware of it. It was tough for me to block it and to continue to play what I needed to play.
"Obviously in those situations, it's not easy, as well, for the opponent.
"Roger, at this time, he doesn't know what am I going to come up with. I was trying to play all or nothing.
"But he definitely played really, really consistently, and served really well throughout the match."