After missing the Australian Open and Qatar Open due to a muscle ailment sustained during his long-awaited comeback event in Brisbane in January, Nadal was set to play in the Indian Wells Open.
The 22-time Grand Slam winner spent an extended period of time in California, having flown there early to prepare for his Netflix Slam match against Alcaraz.
The Alcaraz match was played on March 3, with the 20-year-old prevailing 3-6, 6-4 (14-12), and Nadal was scheduled to make his long-awaited ATP Tour return on March 7 at Indian Wells.
However, he announced his withdrawal from the event just hours before his match against Milos Raonic, claiming on social media:
"I have been working hard and practicing, and you all know I took a test this weekend, but I don't feel ready to play at the greatest level at such an important event.
"It is not an easy decision, it's a tough one as a matter of fact but I can't lie to myself and lie to the thousands of fans."
Some fans questioned his decision to compete in an exhibition event if he wasn't ready for professional tennis, but former world number one Roddick explained why it made sense.