Four-time former champion Roger Federer has been forced to withdraw from the Barclays Dubai Tennis Championships due to a lung infection, it was announced on Sunday.
The Swiss star picked up the infection last week, according to the ATP website, and has not recovered sufficiently to take his place at the $2 million tournament.
It is the second year running that the world's best player has missed the Dubai event due to injury after succumbing to a back complaint last year.
He is expected to be out of action for a further two weeks and is now scheduled to make his first appearance since capturing the Australian Open title at the BNP Paribas Open in March.
Czech Jan Hernych, who fell in the final round of qualifying, becomes a lucky loser in the main draw, the ATP added.
Spaniard Tommy Robredo takes Federer's place at the top of the draw and will play Julien Benneteau of France in the first round.
Federer has a 25-3 match record in Dubai, picking up titles in 2003, 2004, 2005 and 2007. He was also runner-up in 2006.
Five of the world's top 10 - Novak Djokovic, Andy Murray, Nikolay Davydenko, Jo-Wilfried Tsonga and Marin Cilic - are competing in Dubai later this week.