When a long-time opponent says you're slowing down, it is either time to get re-energized or realize a brilliant tennis career is on the downswing.
"From my point of view he hasn't been moving as well this year and I guess that's one of the reasons he hasn't had much success," Djokovoic said.
"He is moving maybe slower than he used to, but he is still striking the ball really well and on his day is capable of beating anyone."
Federer has commented on back problems and cut back his schedule. Djokovic beat Federer in three sets in the semifinals of the Paris
He is in a group with