Querrey leads feelgood factor in American tennis

By Martyn Herman LONDON (Reuters) - The United States will have six players in the men's and women's singles fourth round on Independence Day on Monday -- the nation's best showing at Wimbledon for 12 years. Sam Querrey, whose stunning defeat of defending champion Novak Djokovic reverberated around the world, will be joined by pal Steve Johnson in the men's last 16. Champion and world number one Serena Williams leads the charge in the women's draw, where she will be joined by older sister Venus,