American number one Mardy Fish has suffered a hamstring injury that could prevent him from competing at the ATP World Tour event in London later this month.
The 29-year-old sustained the complaint earlier today during his Valencia Open match against compatriot James Blake.
In just the second game of the encounter Fish decided that the pain in the back of his left leg was too severe to continue.
The top eight players in the world will meet in the O2 arena for the season finale and Fish currently occupies the final spot.
He can not be overtaken in Valencia, but should he fail to participate in Paris next week then he could lose his spot in the tournament.
