Paris, May 30 (Reporter) British number one Katie Boulter was unable to cause a shock against American seventh seed Madison Keys as the nation's involvement in the French Open women's singles came to an end. Boulter lost 6-1 6-3 to Australian Open champion Keys in the second round, with a lot of self-inflicted damage caused by nine double faults across her eight service games on Thursday. "If you don't have a great serving day against someone like that, you're always under pressure," said Boulter, who was broken five times. "I think almost every service game I hit a double-fault. Against someone of that calibre, you just can't afford to do that." Boulter's exit came a few hours after fellow Briton Sonay Kartal was also knocked out. Kartal, competing in her first French Open, struggled for consistency in a 6-1 6-4 loss to Czech opponent Marie Bouzkova, the BBC reported. The pair followed Emma Raducanu out of the clay-court Grand Slam tournament after she lost to reigning champion Iga Swiatek on Wednesday. All three players are provisionally ranked inside the world's top 50 as their tussle for the title of Britain's leading women's player continues in the grass-court season. Boulter is still out in front at 38th in the world, three places ahead of Raducanu and 18 spots clear of 56th-ranked Kartal...////...