Training hard in the gym during a grand slam tennis tournament?

I picked up this interesting quote from Andy Murray today, after his first round win in the French Open Tennis at Roland Garros. This is the exceprt from the the BBC.co.uk:

Murray revealed he had been on antibiotics since Tuesday for a throat infection which forced him to cut back his training.

"I was told to do half of what I would normally do," Murray said.

"I had to make sure I wasn't tiring myself out too much and getting a lot of sleep. I feel a bit better today but this has been the first day I have been feeling good.

"I'll take tomorrow easy and work hard in the gym on Tuesday."

I realise that professional tennis players have to do physical work all year round, a they pretty much compete all year round. However, I'm surpried to see that Murray is working hard in the gym during a major tournament.

Is this normal practice, or perhaps a sign that he is deliberately working through the French Open with the aim of peaking later on (Wiimbledon). I gather he doesn't have much of a record on clay, and maybe this has influenced his decision?

Any conditioning experts out there, or tennis coaches, that would have a view on this?