MONACO -- It was Rafael Nadal who explained it best.
"Roger [Federer] is playing two to three shots, trying to play more aggressive than before," he said. "He probably knows that on clay, that is more difficult. I wouldn't say it's impossible, but it's much more difficult. I believe that he really does not want to change his mentality, and playing on clay probably makes you change something.
"So I think he is more focused on what he has to do, to be competitive, to be healthy and to keep playing that well. He is focused on doing what is working well for him."
For Federer, the surprise winner at the Australian Open and then, in less of a surprise, the champion at Indian Wells and Miami, that means sitting out the clay season until at least until the French Open.
And as the dirt swing begins in earnest here at the Monte Carlo Masters, Federer will be back home kicking his feet up, which is good news for his rivals.
Those three top rivals of Federer, though, dominated the clay-court season in 2016, which likely factored into his decision to bail on most of this segment of the year. Even a fresh, confident Federer might find it difficult to build on his early-season success on a surface that doesn't offer him quite as much value for his shots.
World No. 1 Murray and Djokovic are returning from similar elbow injuries, which caused them to miss Miami, something that could temper expectations this week.
It was not long ago that Murray struggled to adapt to the clay. But he recently has transformed his game on it, winning two Masters 1000s, Madrid in 2015 and Rome last year, followed by a run to the French Open final just weeks later.
"I just feel way more comfortable moving on [clay] now," Murray said. "I know how to move on clay much, much better. I spent lots of time on it in 2014, 2015, lots of time working on my movement on the clay. Some of the Davis Cup ties helped me as well, so my clay-court season has been sometimes a bit longer. That has helped me a lot, as well."
Djokovic seems focused and relaxed, having accepted in his own mind why, by his own lofty standards, his form dipped in the second half of 2016 after he won the French Open to complete the career Grand Slam.
"Until recently, I haven't taken that whole period of five, six, seven years seriously and [realized] what I've achieved and how much energy I have spent," Djokovic said. "After Roland Garros, I didn't have time to enjoy it. Wimbledon was around the corner, and I had to prepare for the Olympic Games."
Like Murray, Djokovic lost early in Australia and suffered another early defeat in Indian Wells -- two events that have been so good to him in the past. But Djokovic is not about to panic.
"First three, four months of the year haven't really passed the way I would like them to be," Djokovic said. "But I trust myself, trust my capabilities and quality and effort that I put in, so I just have to believe that that process is going to give me sooner or later the results that I want."
Nadal is coming off one of his best-ever starts to the year, reaching three finals including the Australian Open and Miami. As he tries to win Monte Carlo for a record 10th time -- no man in the Open era has won a single event that many times -- he is confident and, perhaps more importantly, smiling.
"It is important because I am enjoying it," Nadal said. "That's the most important thing for me, to be happy playing tennis. When I don't have injuries and I feel I am competitive, that makes me enjoy it and makes me happy, more than winning titles. It is obvious to me that it is important to feel competitive enough to have the chance to compete for the most important thing, and for the things that really motivate me.
"I had that feeling in the first part of the season, and I am working to have that feeling in the next couple of months."