Cesenatico is a port town with about 26,000 inhabitants on the Adriatic coast of Italy. It is located in the province of Forlì-Cesena in the region of Emilia-Romagna, about 30 kilometres south of Ravenna. From Wikipedia
The playful jab follows a tradition of social media ribbing between the two Italian tennis legends that stretches from their 1962 junior debut to their 1976 Davis Cup triumph.
