Rafael Nadal says he is "not 100% sure of anything" after being injured in his quarter-final defeat by Australian Jordan Thompson at the Brisbane International.

The Spaniard, 37, was playing his third match since returning from almost a year out with a hip problem.

Nadal needed a medical timeout when he was 1-4 down in the deciding set.

A winner of 22 Grand Slam titles, Nadal said the pain in his left hip is in a similar place to the injury that required an operation in June 2023, but he hopes this one is just muscular.

It comes just nine days before the start of the Australian Open in Melbourne, which he has won twice.

Nadal, who has dropped to 672nd in the rankings, said of his chances of playing in the tournament: "I don't know. I hope to have the chance to be practising next week and to play Melbourne.

"Honestly, I am not 100% sure of anything now. Then, the next couple of days, let's see how I feel. If I don't feel well, then we are going to do a test and we are going to check it.

"I feel the muscle tired. It is not the same like last year at all because when it happened last year, I felt something drastic immediately. Here I didn't feel anything.

"The only problem is, because the place is the same, you are a little bit more scared than usual. In an ideal world, it is just the muscle supercharged after a few days of effort and a very tough match.

"I have been taking a lot of precaution because I know, after a year, it is difficult for the body to be playing tournaments at the highest level. When things are becoming more difficult, you don't know how your body is going to react."

After wins over Dominic Thiem and Jason Kubler earlier this week, Nadal faced the toughest test of his comeback against Thompson, ranked 55th in the world. Friday's defeat was 33 minutes longer than his victories over Thiem and Kubler combined.

Nadal dropped serve midway through the first set only to respond with a break of his own before accelerating away to take the opener.

Chances to close out the match came Nadal's way in the second set tie-break, but Thompson clung on to force a decider.

From there, the 29-year-old Australian took charge and broke Nadal's serve in the final set, with the veteran unable to recover.

Bulgarian Grigor Dimitrov, who eliminated Andy Murray in the first round, will face Thompson in the semi-finals following a 6-1 6-4 quarter-final victory over Australian Rinky Hijikata.

The other semi-final on Saturday will see world number eight Holger Rune face Russian Roman Safiullin, after their respective last-eight successes against James Duckworth and Matteo Arnaldi.