The film, produced by Aditya Chopra under his banner Yash Raj Films, will see Salman as a wrestler from Haryana.
"Heading to Los Angeles to set the action of#sultan with @larnellstovall. The countdown to the shoot begins," Zafar tweeted.
The "Mere Brother Ki Dulhan" helmer has already started song recordings for "Sultan" with composer duo Vishal-Shekhar.
"Sleepless nights. Song recordings. Music-language beyond boundaries @VishalDadlani @ShekharRavjiani #Sultan," the director posted on his Twitter page.
The female lead for the film is yet to be announced.