Fourth seed Roger Federer was also struggling before Felix Mantilla retired when trailing 6-7 6-4 4-1.

BBC: Hewitt back from the brink

Fellow Argentine Guillermo Coria fared better, the eighth seed seeing off experienced Spaniard Felix Mantilla 7-6 6-1 6-3.

BBC: SPORT | Tennis | Nadal makes confident start in NY

The pair became the latest big-name casualties in Stuttgart after fellow seeds Albert Costa and Felix Mantilla lost on Tuesday.

BBC: Seeds fall in Germany