The run to Roland Garros over the next six weeks will be a test bed for the elite pair, with Djokovic hoping that his superlative hard-court form will translate smoothly to the dirt and Federer banking on the results of a Swiss training stint to polish his game to a glossy sheen.
Switzerland's Federer lost the final at the seaside Country Club a year ago to compatriot Stan Wawrinka.
After arriving on Thursday in the principality and already getting in a pair of hitting sessions on Centre Court, the 17-time Grand Slam winner is ready to make another run at a major title which has eluded him.
The second seed starts against the winner from Frenchman Jeremy Chardy and a qualifier in the second round after the bye given to the top eight seeds.
"I'm feeling good about my game and my fitness," said the 33-year-old Basel native with titles this season from Brisbane and Dubai, plus a final in Indian Wells.
"I feel like I did all the right things to prepare for the clay season."
The Swiss skipped the Miami event won by Djokovic to concentrate on a brief family holiday and a training block near Zurich.
"We are onto clay for the first time in seven months after hard court," he said.
"We'll see, but so far, so good."
Federer said that he will play his pre-French Open run by ear, hinting that competing in Rome next month would be a late decision, with the Italian event possibly replaced by some private training if he feels the need.
"I want to do work that will be useful looking ahead of the french Open and Wimbledon."
Djokovic has been going full-tilt since the start of 2015 and has the trophies to prove it after winning the Australian Open for a fifth time and earning his third career title double with back-to-back top honours on Indian Wells and Miami cement.
The Monte Carlo-based Serb is happy to be playing at home and trying not to think of all the tennis he's already in his legs during in the first quarter of the season.
"I'm not thinking about being tired, I'm just relying on the fitness training I did in the off-season and all the work to get myself into a state of mind where I can sustain high levels of tennis throughout most of year,"
said the eight-time Grand Slam champion, off to his best career start since 2011.
"It's not the first time that I've played so many matches, but that's a positive consequences due to my great results," he said.
"I cannot complain, I'm enjoying my time on court."
The Serb is counting on his fitness to hold up after losing a semi-final to Federer a year ago while plagued with a wrist problem.
"I'm playing some of my best tennis now, hopefully I can follow up as there is a lot more of the season to come," Djokovic said.
"The clay is completely different from hard court, but this is the surface I grew up on," he said.
"This is my home base, I feel comfortable here and have played consistently well in the last few years.
"I just hope to start the clay season like I want to."
First-round play began with only three matches scheduled. Victor Estrella Burgos of the Domenican Republic became the week's first winner as he beat Italian Simone Bolelli 6-4, 7-6 (7/5).