Nadal, citing knee, withdraws in Germany

STUTTGART, Germany, July 7 (UPI) -- Wimbledon champion Rafael Nadal has withdrawn from the $892,000 Mercedes Cup tournament in Germany because of a knee problem.

Nadal defeated Roger Federer in a dramatic five-set match Sunday in winning his first Wimbledon title. After arriving in Stuttgart for the Mercedes Cup tournament, Nadal withdrew Monday.

He won the clay-court tournament in 2005 and 2007 and was seeded first this week.

Seventh-seeded Jose Acasuso was upset in Monday's first-round play at Stuttgart with Albert Montanes claiming a 6-3, 7-6 (7-5) victory. In other matches, Andreas Beck got by Daniel Brands 3-6, 6-3, 6-4 and Michael Berrer beat Eric Prodon 6-3, 6-4.

Juan Martin Del Potro, Pablo Cuevas and Oscar Hernandez also recorded wins Monday.

The 2008 Mercedes Cup title is worth $185,000 to the champion.