Nadal: Tiredness not reason for loss
The 24-year-old world number one played one of the matches of the year to battle past Andy Murray in a three-hour semi-final but he found Federer in sensational form as he went down 6-3 3-6 6-1 in one hour 37 minutes.
"I think is not the right moment to talk about that," Nadal said when asked if he was suffering physically against the 16-times Grand Slam champion.
"The thing is everybody saw the match yesterday, so everybody's free to think his own opinion.
"But I'm not going to say I lost the match because I was tired. What I'm going to say and what I feel is I lost the match because I played against a very good Roger Federer on one of his favourite surfaces. When he's playing like this, it's very difficult to stop him. I had chances, but not enough."
Rather than dwell on his defeat, Nadal preferred to look back on a year he described as the most "emotional" of his career.
After going 11 months without a title he returned to form in Monte Carlo in the spring, winning on the Riviera clay for a sixth consecutive year, and the confidence flooded back.
From then on he was virtually unstoppable, winning the French Open and Wimbledon back-to-back for a second time and completing his career Grand Slam by winning the US Open.
It was all a stark contrast to 12 months ago at the London finale when he failed to win a set in three matches.
"This was a fantastic week for me," Nadal said. "Beating four top-eight players in the same week on a difficult surface for me. I think that's never happened in the past.
"There have been a lot important moments for me during the season. I think it was a very emotional season.
"There were difficult moments in the beginning, but after a tough time, I was able to play with ambition all the season and I managed to have chances to win and keep winning.
"Once I won the first tournament in Monte Carlo, everything was easier, all the pressure and anxiety left and I started to play really well."