Rafael Nadal will have a scan on an abdominal injury before his Wimbledon semi-final after it almost forced him to retire from his last-eight match.

Nadal had a medical timeout and somehow - even he said he did not know how - came from behind to win in five sets.

"[Retiring] is something that I hate to do," the 36-year-old said.

"So I just keep trying, and that's it."

He also had strapping on his abdomen during his previous match but said the pain had got worse during Wednesday's 3-6 7-5 3-6 7-5 7-6 (10-4) victory over American Fritz.

"It's obvious that today is nothing new. I had these feelings for a couple of days. Without a doubt, today was the worst day," he said.

"[There has] been an important increase of pain and limitation. Tomorrow I am going to have some more tests."

Nadal says he is well used to pain, and playing with problems, during a career in which he has won a men's record 22 Grand Slam singles titles.

Only last month, he won his 14th French Open title without being able to feel his left foot as it was anesthetised because of a chronic condition.

But he will not jeopardise his health when deciding whether he can play Kyrgios on Friday to continue his bid for a calendar Grand Slam, having already won the Australian and French Open titles this year.

"[There is] something more important than winning Wimbledon, that is health," he said.

He went off court during the second set against Fritz, with the doctor giving him anti-inflammatories and painkillers and the physio trying to relax the muscles.

"It's difficult," he said. "Nothing can be fixed when you have a thing like this. That's it.

"I just wanted to give myself a chance. [It is] not easy to leave the tournament. Not easy to leave Wimbledon, even if the pain was hard."

Asked what he thought his chances were of playing on Friday, Nadal replied: "I don't know. Honestly, I can't give you a clear answer because if I gave you a clear answer and tomorrow another thing happens, I will be a liar."