French tennis star Jo-Wilfried Tsonga\'s hopes of making the end of season ATP Masters finals suffered a blow on Tuesday as he was forced to withdraw from the Valencia Open with a back problem. The 27-year-old - who presently occupies the eighth and last spot for the November 5-11 tournament - had called for the physiotherapist in only the second game of his first round match with Belgian Xavier Malisse. However, despite the treatment the tournament second seed - who got to the final of the Stockholm Open last Sunday - had to give up when trailing 3-1 in the first set. The Frenchman\'s evening slightly improved when his closest challenger for the Masters spot Janko Tipsarevic was also forced out, retiring in the first set of his clash with Gilles Simon with the Serbian trailing 5-4.