Nadal to undergo surgery, Federer to surpass him for No. 2

Rafael Nadal plans to have surgery for appendicitis following the ATP World Tour Finals in London, but will play on until then as scheduled.

The Spaniard was diagnosed with the condition before the Shanghai Masters, but chose to take antibiotics to control the inflammation rather than having immediate surgery. Though physically sound, the medication left him light-headed and he was been unable to train properly before the tournament. He lost to Feliciano Lopez in his opening match in straight sets. It was his second tournament in a comeback from a wrist injury that sidelined him for three months.

Nadal admitted that surgery would be required to ensure the condition did not reoccur, and said he did not want to develop problems during a tournament.

''I talked to my doctor in Spain, and there is a lot of risk when it has already happened to you once," Nadal said. ''My answer today, honestly, is that I'm going to do it after the World Tour Finals. You never know, depends on how things improve.”

"If it is now under control, it is obvious that [it] will come back, and I do not want to come back and be the same again when you arrive in Australia, in Indian Wells, or Miami, or Roland Garros, and I'm going to do before the end of the year," he said.

UPDATE:

The world No. 2, who will drop to No. 3 next week, is expected to play Basel, Paris, and then the ATP World Tour Finals in London. Roger Federer will return to No. 2 in the rankings, having narrowly won his match in the second round of Shanghai while Nadal fell at the same stage.

Federer needed to go further in the tournament than Nadal to surpass him, and did so by saving five match points in a scratchy performance in his opener. It is his highest ranking since before the 2013 French Open.

The 33-year-old was unmoved by the rankings change, saying, "It's good news. Better moving up than down. Nothing more than that. Clearly I want to move up, play well. Others not playing so well. Clearly Rafa hasn't played for some time—take advantage of that. Plus I didn't win a Slam this year, so it shows even more so how consistent I've actually played and how much I played this year, so I guess I deserve it from that standpoint."

Federer holds the all-time record for weeks at No. 1.