World No. 1 Novak Djokovic tells reporters in Basel that the back problems he suffered after he won the U.S. Open was the worst injury of his career. "I'm only just back from the biggest injury of my career. It was a big task for me to have played really well," said the Serbian after beating Xavier Malisse 6-2, 4-6, 7-5 in the first round. "I could do nothing for four-and-a-half weeks, I've only been hitting for a week-and-a-half. That's not enough to play at my best. I've lost rhythm."