World No. 2 reaffirms commitment to Davis Cup.
"The tour is very tough. It's only meant for the really strong in the head," says 20th-ranked Aussie.
World No. 1 shared words of advice for upstart Aussie talent in Shanghai.
The 21-year-old Montreal native is still suffering from symptoms from a concussion that happened on September 4.
The Spaniard may have found his confidence once and for all with these three fantastic return winner in Shanghai.
The 25-year-old Czech will make her fifth consecutive appearance at the WTA Finals.
"Nothing is impossible. I have that kind of mindset. I know that it's still a long way to break (Federer's) record," said world No. 1.
