The Spaniard spent most of the time hitting forehands and backhands, and though he did practice some serves, they were at a vastly reduced speed.
Spanish newspaper Marca reported Thursday that Nadal has a 7-millimeter tear in one of his abdominal muscles, but that he intends to play.
Nadal is on the official order of play on Friday and has a little extra time to recover as he is scheduled in the second semifinal.
Nadal wore tape over part of his abdomen and required treatment, including painkillers, during his thrilling five-set victory over Taylor Fritz in the quarterfinals on Wednesday.
After his win, Nadal admitted he did not know if he would be ready to take on Kyrgios.
"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," he said.
Nadal, 36, is trying to win Wimbledon for the third time and the first time since 2010.
Victory would give him a record 23rd Grand Slam title and having won the Australian Open and French Open, would put him three-quarters of the way to the calendar-year Grand Slam, something no man has done since Rod Laver in 1969.
Nadal said Wednesday that he is "used to hold pain and to play with problems."
"Knowing that, when I feel something like I felt, that is because something is not going the proper way in abdominal, no?
"But let's see. 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. Have been an important increase of pain and limitation. And that's it, yeah. I managed to win that match. Let's see what's going on tomorrow."
ESPN has contacted Nadal's media representative for an update on Nadal's fitness.