World number two Rafael Nadal withdrew from the Mexican Open due to a hip injury.
The Spaniard was set to make his first appearance since the Australian Open, where he exited in the quarter-finals, as the top seed in Acapulco.
But Nadal, 31, felt the same injury he suffered in Melbourne in training on Monday, seeing him withdraw from the ATP 500 event.
"I believe that all the necessary cares had been taken, I arrived to Cozumel to work on my adaptation," the two-time champion said.
"But yesterday in the last training before starting the tournament, I noticed a puncture in the same area of the problem I had in Australia. I do not know what it is yet, but it is in a similar line to what happened in Australia.
"Maybe it is a minor situation but the reality is that it is not clear yet and until it goes down a bit and the tests are done, it will not have the exact diagnosis.
"The doctors told me that I cannot play because there is a risk of increasing the injury."
-- Abierto Mexicano (@AbiertoTelcel) February 27, 2018
Nadal's withdrawal left German Alexander Zverev as the top-ranked player in the draw.