Familiar face helping 2015 French Open champion train for comeback.
Knee pain knocks world No. 4 out of Madrid Masters.
Former No. 1 needs more training time.
The Swiss will bid for his 18th grass-court title at the Mercedes Cup from June 11-17.
The Swiss went down with a calf injury before her first match in Morocco.
Former No. 1 says the world's top two will continue to rack up Slams.
A funny thing happened to Frenchwoman on the way to practice.
