Novak Djokovic admitted to being concerned by the gruelling schedule on the ATP Tour, while adding about his happiness at ending the year as the world number one for the second straight season.
Djokovic is taking part in the Paris Masters this week, right after which the ATP World Tour Finals will take place in London.
Pointing out to the fact that is doesn't make much sense to hold a Masters tournament right before the big season-ending tournament, Djokovic said the schedule was taking a toll on his body.
"It is a big challenge," the Serbian told reporters. "Obviously I'm sure all the participants in London will agree that this is definitely not something that goes in the favor of us preparing for the most important event in the end of the year."
The Paris Masters scheduling prompted Roger Federer to withdraw from the tournament, having already participated in his home meet - The Swiss Indoors Basel - last week. Djokovic and Andy Murray have not played since meeting in the final of the Shanghai Masters a couple of weeks back.
"This is the schedule," he added. "It is the way it is. We have to adjust, we have to accept it. Unfortunately, there is no other options at this moment.
"But we will discuss this matter after we finish this season. Maybe we can try to find some other way.
"This season is shorter by two weeks. Now we have a two weeks longer off-season. Maybe that was the sacrifice we had to make.
"There are still some options on the table about this (pre-London) week. Maybe we can move it around so we can make it more adjustable for the top players.
"Physically I feel good now, but I'm not the freshest guy on the Tour because I have had a long year. But I want to try to hold on these two weeks and perform my best, and then go to holidays."
Djokovic said he was satisfied to finish the year as the world number one. "It feels very satisfying, and of course I'm very happy to be able to finish the season as No. 1," he said. "Obviously that serves as an indication of how good the season was for me.
"It was very difficult to follow up after 2011 and to expect, well, from myself to repeat what I've done in that season. But winning one Grand Slam this year, and five titles so far and being very consistent with my results helped me to be in this position right now."
The Serbian is now determined to finish the year on a high. "I'm very proud of the achievements," he added. "It was a very good year for me, but it's not over.
"There are two more very important tournaments to come: indoors here in Paris Bercy, and then London next week. I just want to try to focus on those tournaments (to end) the year in the best possible way."
