The British number one came into London as the number three player in the world, and was competing in a group with David Ferrer, Novak Djokovic, and Tomas Berdych.
When asked about the decision to withdraw Murray responded,
“It's just a really difficult decision to make because it's one of the best tournaments in the year to play and it's something that you also work all year to play here, as well.”
Murray had only lost one match since the U.S. Open and was an odds on favorite to take the title.
World No. 9 Janko Tipsarevic will take Murray's place for the remaining two matches of group stage, and possibly more, should he advance.