Saturday September 4th Schedule at the US Open?

[vmosrafa08]

I want to see Novak Djokovic play, but I was wondering if he is going to play during the day, or during the evening session. Tonight he played during the evening session and federer played during the day session. Does that mean that they will switch in two days?

If anyone knows, please let me know because I want to buy tickets as soon as possible.

Here is a link to the schedule of play (It does not include the schedule for Saturday, unfortunatey)

http://www.usopen.org/en_US/scores/schedule/schedule10.html

Thanks so much!