The 25-year-old, who won the French Open earlier this year, has also revealed that she has recovered from two recent illnesses.
"Winning the French Open was such a confidence booster for me. It was the one that I hadn't won and it was the one I really wanted. I always thought it was going to be the most challenging for me. To have all those four are so meaningful, and obviously, this is the last one of the year," she told the CBS Morning Show.
"We've had a crazy schedule. To come into the Open, it's like this is it for the year. We still have more tournaments after that, but as far as the big one, it's the one we really look forward to. I came back from the Olympics and was supposed to play a tournament in Montreal, but had a stomach virus.
"Besides, it's been a very busy summer, so I decided to shut it down before the US Open and come here a little early and start practicing. It's fun to be back in New York. I love the energy and the city. The US Open is the most fun one yet."
The US Open begins on August 27.