The world No.2 was expected to challenge his compatriot Feliciano Lopez in the first round of the Mexican Open in Acapulco on Tuesday, but he has pulled out the tournament without striking a ball in anger.
The 31-year-old has suffered a recurrence of the thigh issue which forced him to retire from his quarter-final duel with Marin Cilic at the Australian Open in January.
“It’s a tough one of course,” Nadal told the ATP world tour. “In my last practice with Adrian Mannarino I felt something. I went to the hospital to check it, and had an MRI [scan].
“I still have some liquid there [in the leg] and I need to keep doing tests to know exactly what is going on. The spot is really similar to Australia, so we need to be sure what’s going on in the next couple of days – and then we are going to work hard to recover as soon as possible.”
The Spaniard faces a race against time to be fit for Indian Wells – the first Masters of the year – which begins next Thursday.
“It’s impossible for me today to say something realistic about whether I’m going to be in Indian Wells or not,” added Nadal. “My goal is to be there and I’m going to work to be there. At the moment I can’t say yes or no, but I hope the test will be as positive as possible and then we will see.”
In the pick of the first round matches that did take place, Denis Shapovalov reigistered a big win over Kei Nishikori.
The Canadian teenager bounced back from first set disappointment to defeat the former US Open finalist 6-7(3) 6-3 6-1. The Japanese looked weary in the searing heat, and he offered little resistance in the decider.
Matthew Ebden took out the defending champion Sam Querrey 6-3 1-6 7-6(5) while Juan Martin del Potro thumped Mischa Zverev 6-1 6-2 in just 61 minutes.