"I don't feel tired at all," he admitted. "Mentally I feel really fresh. Normally after playing a match with Novak, you will feel a bit fatigued. I feel fine.
"Anybody that knows me knows I won't go into the match happy with just having a silver medal. I go into the match 100% trying to win. I'll give everything I can on the court.
"There's obviously huge motivation to try to win a gold medal. Winning against Roger in a match like that is fairly significant. I'll be desperate to win.
"Now I'm in the final, I have the chance to win a gold medal. I'm not going to have that chance for another four years. So I'll give it everything I can to try to do that."
Murray is also in his first Olympic final, having lost to Lu Yen-Hsun Lu of Taiwan in the first round in Beijing four years ago.
But Federer said of Murray: "He got amazing crowd support in the Wimbledon final. I was able to handle that. But there's never a guarantee. I don't know how much the crowd plays in the outcome of the match.
"He's such a great player but I've been around as well. I think it should be a great match." http://www.bbc.co.uk/sport/0/olympics/19123124