Ali is the joint-record scorer for Qatar, having matched the retired Mansour Muftah’s tally of 42 goals, and will be supported by midfielder, and captain, Hassan Al-Haydos, who will be making his 170th international appearance.
Manager Felix Sanchez Bas will likely set his side up in a caution manner for the country's first ever World Cup game.
Ecuador, by comparison, are World Cup veterans as they prepare for their fourth tournament, and first since 2014. They will be looking to get out of the group stage for just the second time.
West Ham fans will remember Enner Valencia. Now his country's captain, he leads the line alongside Gonzalo Plata and Romario Ibarra.
Angelo Preciado starts at right-back, while Brighton star Moises Caicedo is in midfield, supported by Seagulls team-mate Pervis Estupinan at left-back.
Qatar XI: Al Sheeb; Al-Rawi, Khoukhi, Hassan; Miguel, Hatem, Boudiaf, Al-Haydos, Ahmed; Ali, Afif
Ecuador XI: Galindez; Preciado, Torres, Hincapie, Estupinan; Plata, Mendez, Caicedo, Ibarra; Estrada, Valencia