Nadal, perhaps Spain's biggest name in sports, thanked doctors, nurses, police, the armed forces and others on the frontlines for their work in trying to contain the spread of the virus and treat those infected.
He also sent a message of condolences to those who have lost loved ones to Covid-19 and to those who are infected by the virus.
Noting the unity the country has shown, Nadal encouraged people to follow protocols laid out by health workers and others to stay in their homes to help limit the spread of the contagion.
The outbreak in Spain is Europe's second worst and on Sunday (March 22) the government sought to extend a state of emergency it has imposed until April 11.
The nationwide state of emergency, announced on March 14 and intended to last 15 days, bars people from all but essential outings.
The death toll in Spain from coronavirus rose to 1,720 on Sunday from 1,326 the day before, while the number of registered cases rose to 28,572 from 24,926, according to Health Ministry's data.