Juan Martin del Potro was an early round action at the U.S. Open.

The Argentine star won the 2009 U.S. Open and is slowly returning to form after a wrist injury cost him most of the 2010 campaign. He is seeded 18th this year and followed up an easy opening-round win over Italy's Filippo Volandri with a 6-2, 6-1, 7-5 triumph on Friday over fellow Argentine Diego Junqueira.

Another early winner Friday was France's Julien Benneteau, who posted a 6-4, 6-4, 6-4 victory over Denis Istomin of Uzbekistan. Benneteau, coming off a runner-up finish to John Isner last weekend at the Open tuneup in North Carolina, will next meet the winner between Andy Roddick and Jack Sock.

Roddick, the 2003 Open champ, will close the night session at Arthur Ashe Stadium on Friday evening.

Other top men scheduled for second-round play Friday afternoon include defending champ Rafael Nadal and Andy Murray. Nadal, seeded second this year, will take on Frenchman Nicolas Mahut and the fourth-seeded Murray will square off against Dutchman Robin Haase.