There is no shortage of tennis courts in San Juan [1]. Many of the large hotels have courts. In addition, there are several public courts, including: Caribbean Mountain Villas Tennis Court (Carr. 857, km 857, Canovanillas Sector, Carolina, 787/769-0860); Central Park (Calle Cerra off Carr. 2, Santurce, 787/722-1646); Isla Verde Tennis Club (Villamar, Isla Verde, 787/727-6490).
Links:
[1] http://www.moon.com/destinations/puerto-rico/san-juan