Remind me, when an American wins the French Open, do they have to speak French to address the crowd or can they speak English?

Juan Martin del Potro wanted to address the crowd in Spanish, his native language.  He politely asked whether he could.  Notice how Richard Enberg responded that they were running out of time and turned to introduce the Lexus executive.  Only after del Potro asked again, was he allowed to.  Nice how we ask international athletes to come here to compete, as long as they speak like us when they win.