OMNISPORT 

Roger Federer has withdrawn from the Miami Open after being struck down by a stomach virus.

Tournament organizers announced the Swiss had been pulled ahead of Friday's second-round meeting with Juan Martin del Potro.

World number three Federer, a winner of the tournament in 2005 and 2006,  will be replaced by lucky loser Horacio Zeballos.

Federer, a 17-time grand slam champion, had been due to make his return in Miami after undergoing surgery on a knee injury.

The 34-year-old revealed this week that he suffered a torn meniscus while preparing a bath for his twin daughters.