Using its main players, Spain gained a 88-61 victory against Iran.
Iran is holding a camp in Spain in preparation for the Tokyo Olympics. The team had earlier held a camp in Japan, staging friendly matches with the Asian team.
The second match between Iran and the two-time World Cup winner will be held on Monday in Madrid.
Iran is drawn with the US, France, and the to-be-determined winner of the FIBA Olympic Qualifying Tournament in Canada in Group A of the Olympic Games.
MAH/ 5249814