Rafael Nadal's hopes of completing a rare calendar year Grand Slam ended on Thursday when the Spaniard pulled out of his highly-anticipated Wimbledon semi-final showdown with Australian Nick Kyrgios with an abdominal strain. "I have to pull out of the tournament as I have been suffering with pain in abdominal," said the 36-year-old, the holder of a men's record 22 Grand Slam titles. "I can't imagine winning two matches with this (pain). For me the most important thing is happiness rather than the title even though everyone knows how much effort I put into this as I can't risk being out of the sport for two to three months.