Kei Nishikori withdraws from Sony Open, Novak Djokovic advances to final

Kei Nishikori took down Roger Federer 3-6, 7-5, 6-4 in the quarterfinals. (Matthew Stockman/Getty Images)

Kei Nishikori on Friday withdrew from the Sony Open with a left-groin injury, sending Novak Djokovic into Sunday's final.

Nishikori needed three sets to defeat both No. 5 Roger Federer and No. 4 David Ferrer on back-to-back days to advance to the semifinals. But it appears the 48 hours of rest weren't enough to recover from the more than five hours he spent on court during both matches combined.

Nishikori wrote a message to fans on Facebook:

Very sorry to say that I have to pull out today. Very disappointed and I am obviously very sorry for any fans that wanted to come out for this match. This tournament is very special to me and look forward to coming back in the years to come. I will work with my medical team to be back healthy as soon as possible.