Smith (ankle) was a limited practice participant Friday, but he has been ruled out for Sunday's game against the Vikings, Michael DiRocco of ESPN.com reports.
The rookie second-round pick was limited in practice all week, but he will be sidelined for a third straight game due to an ankle injury. Smith's next chance at suiting up will be Week 11 against Detroit on Sunday, Nov. 17. Jordan Jefferson and Jeremiah Ledbetter will be the primary backups at defensive tackle behind starters DaVon Hamilton and Arik Armstead.