Rafael Nadal will miss the 2014 ATP World Tour Finals after deciding to undergo a season-ending appendicitis surgery, the Spanish tennis superstar announced on Friday.

Nadal was diagnosed with appendicitis during the Shanghai Masters, but he decided to delay surgery and took antibiotics in the hope of making it into the ATP World tour Finals in London next month.

However, the 14-time Grand Slam champion announced that he has already decided to undergo surgery on Nov. 3, saying that he will also not compete in the upcoming Paris Masters.

"It's the day to say goodbye to the season," Nadal said after losing to 17-year-old Borna Coric in the quarterfinals of the Swiss Indoors on Friday via ESPN. "It's been a very hard year for me, mentally and physically. I'm not going to play Paris and London, I'm not competitive enough for that. I need to do the surgery for my appendix."

The 28-year-old tennis superstar also added that his back is also not feeling too well over the past several weeks, saying that he will look to become 100 percent healthy before returning to action next year.

"I need to work on my back a lot," Nadal added via The Guardian. "Since Australia I'm not 100% recovered. That needs time and a period of five weeks to work hard again. I need to try to fix all the things that bother me. I'm going to work for one month in December and I will be back at the start of 2015."

Nadal also insisted that he wanted to play in London and in Paris, but he believes that he is not fit enough to win both tournaments because of his appendicitis.

"Every day I felt a little bit more tired," Nadal said. "I tried to practice to try to get fit but it was not possible. It's difficult to play and compete when you're not able to practice weeks in a row. I'm not a player who competes to try to be in quarter-finals. I try to compete with chances to win tournaments."