World Champion Viswanathan Anand let go off an excellent position after losing to Hikaru Nakamura of United States in the fourth round of the London Chess Classic on Wednesday.After 11 successive draws in a row, including nine draws in the just concluded Tal Memorial at Moscow, the loss on Wednesday proved to be too costly for Anand as he fell to joint seventh spot in the nine-player round robin tournament, wherein the soccer-like scoring system is in use.World number one Magnus Carlsen played out a draw with Vladimir Kramnik of Russia and was joined by Luke McShane of England at the top the tables with eight points after four rounds.McShane, an amateur by choice, continued his excellent run and won against compatriot David Howell.In another game of the day, former world championship challenger Nigel Short opened his account at the expense of country-mate Michael Adams.With Carlsen and McShane in front, Nakamura now occupies the sole third position with seven points, while Kramnik is in fourth spot with five points in his kitty.Not far behind is Aronian with four points so far and Nigel short jumped to the sixth spot with three points. Anand, Howell and Adams share the seventh spot with just two points apiece.There are five more rounds still to go, and Kramnik, Aronian, Anand and Short have played one game less than the others, and this may prove crucial in the rounds to come.It was a King's Indian defense by Nakamura and Anand went for the Bayonet attack and chose a variation that Nakamura had faced a year back against Kramnik.It was clear that Anand was much better prepared as Nakamura lost an important tempi to let the World champion enjoy a substantial advantage.