"I prefer not talking about it. It's just something I carry for the last seven days," said the Serb.
The 20-year-old is considering an injection and perhaps surgery.
World No. 1 beats Gabashvili 6-4, 6-1; No. 4 seed Federer cruises to 6-1, 6-2 win over Stepanek.
The Swiss says he will sit out tournaments, including French Open if necessary, to be with wife Mirka when she gives birth.
No. 6 seed posts 6-1, 6-4 win; Cibulkova, Mayr-Achleitner also advance.
Rafa rules on red, that we know. Who else can make hay on clay?
As the tour changes continents and surface, which players are in line for a spring renewal?
Like the Masters without Tiger, the clay season wouldn't have the same edge without Rafa.
Who's going to win the first big men's clay event of 2014? A Monte Carlo preview.