"Lucky loser" Florent Serra will face 2009 U.S. Open champion Juan Martin del Potro in the tournament's first round after David Nalbandian withdrew.

Nalbandian pulled out Tuesday because of a strained muscle in his chest, and the U.S. Tennis Association determined his opponent Wednesday morning, several hours before the match.

Serra, a 116th-ranked Frenchman, lost to American Bradley Klahn in the third round of qualifying.

Del Potro is seeded seventh.

Nalbandian was also scheduled to play doubles with Eduardo Schwank, and they will be replaced by Brazilians Thomaz Bellucci and Joao Souza.