French Open finalist Rafael Nadal has pulled out of next week's event at Halle in Germany.
The Spaniard, who will face fellow Spaniard David Ferrer in the final at Roland Garros on Sunday, has cited "health" reasons for his absence.
"It is a pity and unfortunate Rafael cannot come. But I understand his decision... his health is the top priority," said Halle tournament director Ralf Weber in a statement.
The Spaniard will win his eighth French Open should he secure victory this weekend.