Nadal said he was still uncertain what his injury but said he was feeling pain high in his right leg. “Not the hip,” said Nadal, who plans to have a magnetic resonance imaging test on Wednesday.
In the semifinals, Cilic will face Kyle Edmund, an unseeded player from Britain, who upset No. 3 seed Grigor Dimitrov, 6-4, 3-6, 6-3, 6-4, earlier in the day in Rod Laver Arena.
Nadal’s retirement means there will be no rematch with Roger Federer in this year’s Australian Open final. Federer beat Nadal in a five-set thriller in 2017 to win the title, but Federer, who will face Tomas Berdych in the quarterfinals on Wednesday, is now the only member of the so-called Big Five, who is still in contention at Melbourne Park.
The years of competing at the highest level are taking their toll on that elite group. Andy Murray underwent hip surgery earlier this month in Australia after withdrawing from this tournament. Novak Djokovic and Stan Wawrinka managed to play after taking six-month breaks from competition because of injuries, but both were diminished in Melbourne.
Wawrinka, returning from knee surgery, lost in the second round to the 97th-ranked American Tennys Sandgren. In a fourth-round loss to the 21-year-old South Korean Hyeon Chung, Djokovic was frequently wincing in pain, his right elbow still not sufficiently healed after his extended break.
Sandgren and Chung will play each other for a spot in the semifinals on Wednesday.
Nadal expressed concern for the series of injuries sustained by leading players in the last year.
“It’s not the right moment to say for me, but somebody who is running the tour should think a little bit about what’s going on,” Nadal said. “Too many people getting injured.”
Nadal said tennis authorities needed to think about the long-term health of the players.
“There is life after tennis, so I don’t know if we keep playing in these very, very hard surfaces what is going to happen in the future with our lives,” he said.