He practised at Wimbledon on Thursday but in his 7.20 pm (1820 GMT) press conference he admitted defeat.

The Spaniard, who said he had had an issue with his abdominal muscles for the past week, admitted he had been struggling with what decision to make all day.

Nadal had been still on course to win all four majors in the same year after he won the Australian Open before collecting a 14th French Open crown.

The last man to achieve the feat was Australian Rod Laver, in 1969.

But Nadal said he wanted to put his health first, fearing that playing on would only worsen the injury.

"I never thought about the calendar Slam, I thought about my diary and my happiness," said Nadal.

"I made my decision because I believe that I can't win two matches under these circumstances," he added. "I can't serve.

"It's not only that I can't serve at the right speed, it's that I can't do the normal movement to serve."

Nadal struggled with crippling foot pain at the French Open but was cleared to play at Wimbledon after treatment.

He said he expected the injury to take up to four weeks to heal but that he would be able to practise from the baseline in a week's time.