Juan Martin Del Potro has been knocked out of the Valencia Open at the semi-final stage.
The Argentine, who lost 6-4, 7-6 to Marcel Granollers of Spain, now faces a battle to reach the season-ending ATP World Tour Finals.
Only the top eight players in the world rankings play in the Tour Finals in London this month.
The 23-year-old would have moved up to ninth in the world with victory over Granollers but must now perform very well at next week's Paris Masters if he is to have any chance of reaching the Tour Finals.
Granollers will play either defending champion David Ferrer or wildcard Juan Monaco in the Valencia Open final on Sunday.
The Spaniard reached the final of this tournament last year as well but he lost out to Ferrer.
