Rafael Nadal, Novak Djokovic Highlight US Open Field

Novak Djokovic (L) and Rafael Nadal will be the players to watch out for in US Open 2014.

Defending champion Rafael Nadal and top-ranked Novak Djokovic highlight the men's field at the 2014 U.S. Open.

The United States Tennis Association said on Thursday that Roger Federer, Andy Murray, Juan Martin del Potro and Lleyton Hewitt will also be among those who received direct entry into the hard-court Grand Slam tournament.

Nadal will defend his title in the tournament that begins Aug. 25 in New York. Djokovic will put a streak of four straight appearances in the final on the line.

Among Americans receiving direct entry were John Isner and Sam Querrey. The men's final is scheduled for September 8.