A stomach virus has ruled Roger Federer out of the Miami Open, with lucky loser Horacio Zeballos replacing the Swiss.
Roger Federer has withdrawn from the Miami Open after being struck down by a stomach virus.
Tournament organisers 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.
"I feel bad for the tournament and the fans, as I have rarely ever had to withdraw at such short notice," Federer said in a statement.
"I have not felt great for a few days, and unfortunately it got worse in the last 24 hours. I was really excited to have my comeback in Miami but am in no condition to play. I tried to warm up this morning, but it was clear that I could not compete."
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.