The U.S. Open will be played August 28-Sept.
Federer also beat Nadal in the final of the Miami Open to complete the "Sunshine Double" in March.
"In general, I know that, when he takes a break and is refreshed and ready to go, happy to play and motivated... this is one of its greatest strengths".
The Arthur Ashe stadium was nearly empty when pre-tournament favourite Garbine Muguruza opened her campaign in round one on Monday, and former men's champion Marin Cilic had only a few more spectators to entertain in the following match.
Marin Cilic, the fifth seed who has had his own injury problems recently, takes Murray's spot as the second seed, according to Grand Slam rules, and will play Tennys Sandgren today. No. 4 Alexander Zverev.
Rafael Nadal has a lot going for him at the US Open 2017. Djokovic, who won the U.S. Open in 2011 & '15, is done for the rest of 2017 with an elbow injury. Muguruza won Wimbledon back in July but hasn't been past the second round in four previous U.S. Opens. She was banned from the tour for 15 months - returning in April - after testing positive for the newly banned drug meldonium at the 2016 Australian Open. Believe it or not, those two legends have never played a match against one another at the U.S. Open.
The odds surrounding the US Open are of the best we have seen all year.
"I don't think we're both thinking that far ahead".
The two veteran stars put on a show in a superb five-set Australian Open final won by Federer earlier this year. Sharapova then was going to try to qualify for Wimbledon in June, but she ended up skipping the grass-court portion of the season because of an injured left thigh. She reached the semis at Wimbledon.
In a pre-tournament presser the 31-year-old said, "If I am in semi-finals, no". She came out last night and dominated the first and third sets, sending Halep home in the Round of 128, and leaving the door open for an awesome and unpredictable US Open.
Williams' sister, 23-time major champion Serena, is not playing in the U.S. Open because she is pregnant and expecting to give birth in September. Also in the mix are Angelique Kerber (last year's champion), eighth seed Svetlana Kuznetsova, tenth seed Agnieszka Radwanska and fifteenth-seed American Madison Keys.
Eight women have a chance to ascend to the No. 1 ranking based on their results at this U.S. Open.
Federer pulled out of his last tournament in Cincinnati two weeks ago with a bad back but says he's fine now.