Rafael Nadal says he has made the “tough” decision to withdraw from Indian Wells as he is not yet “ready to play at the highest level”.The 22-time grand slam singles winner has been off the tour since suffering a muscle injury in Brisbane in January. He was set to mark his return with a first-round match at Indian Wells against Canada’s Milos Raonic on Friday. However, in a post on social media, the 37-year-old said he is not yet ready to compete.“It is with great sadness that I have to withdraw from this amazing tournament at Indian Wells,” he said. “Everyone knows how…