Federer was stunned by Kei Nishikori in his opening group match at the ATP Finals on Sunday, falling to a straight-sets defeat.
It led to the Swiss star holding a crunch meeting with his coaching team and they came to the decision to take a day off to rest.
The move paid dividends as Federer responded by easing past Dominic Thiem in his second rubber.
He followed the same routine before his victory against Kevin Anderson last night which saw the 20-time Grand Slam winner progress through Group Lleyton Hewitt in top spot.
Federer will discover his semi-final opponent today as Group Guga Kuerten draws to a close.
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But the 37-year-old will have his feet up while waiting to find out his fate.
“I’m feeling great. I’m very happy that I still have energy left in the tank. Mentally I feel fresh, to be honest,” Federer said.
“Well, look, everybody does it differently.
“Everybody has got different coaches and entourage that give you different advice.
“Look, I’m a big believer in vacation. I’m a big believer in taking time off sometimes. When I go to work, I go hard, I go the right way, I go professional about it with my team.
“I didn’t think of taking a day off, to be honest, after the Nishikori match. I thought, ‘What are we going to do? Where are we going to train?’
“They said, ‘How about a day off?’
“I said, ‘Sure, I’m happy for a day off. It’s only if you guys want it.’
“This is how we took the decision quickly. The day after Nishikori, as we realised it made me happy, relaxed, motivated for when I do come on court, that it’s working. We kept that. I didn’t practice [Wednesday]. I doubt that I will practice [Friday].
“I think if I can’t practice on Centre Court, there’s no reason to go on a different court, feel a different type of atmosphere. Here it’s great.
“I can warm up with the matches with great intensity and I’m ready to go.
“I played so much of my career, so much this season already, especially recently, we just don’t feel the urge of having to work on anything. It’s all about matches at this point.”
Federer was practising at Queen’s Club in west London prior to the season-ending event.
But he was unhappy with the grass courts as they are a different pace to the hard court at London’s O2 Arena.