Serena posts on Twitter for first time since giving birth to baby girl.
10-day event would offer ATP rankings points before Australian Open.
Hit-and-run tennis with a twist.
Roger Federer had a feeling he was in trouble against Juan Martin del Potro.
World No. 1 on what he admires most about Federer.
Roger or Rafa? CoCo Vandeweghe has a clear favorite.
Top seed assesses Vandeweghe's game bluntly after US Open quarterfinal loss.
