The Open Champion, who became the first Italian to win the Race to Dubai last season, tees off at 11.27 on the opening morning at Chapultepec Golf Club.
Phil Mickelson will begin the defence alongside fellow Americans Dustin Johnson and Justin Thomas.
Mickelson became the oldest winner of a World Golf Championships event when he beat Thomas in a play-off in Mexico last year and he returns looking to beat off competition from some of the world's best players to claim a fourth WGC title.
The 48-year-old will begin his first round at 11.51 on Thursday, joined by five-time WGC-winner Johnson and World Number Four Thomas.
World Number Two Brooks Koepka will also start his first round on Thursday morning, teeing it up alongside Rory McIlroy and Bubba Watson in a star-studded group.
Tiger Woods, who is looking to add to the 18 WGC events he has won in his long and storied career, will play with home favourite Abraham Ancer and Omega Dubai Desert Classic champion Bryson DeChambeau in the afternoon, teeing off at 13.03.
Also starting later in the day are Spain's Jon Rahm, 2018 Masters Tournament winner Patrick Reed and Rickie Fowler who get under way at 12.51.