By Daniel Kreps Guns N’ Roses kicked off their 2026 world tour Saturday in Monterrey, Mexico, delivering a 26-song set that included the live debuts of “Nothin'” and “Atlas.” Both tracks — which had been kicking around since the Chinese Democracy sessions and were demoed even earlier — were finally released in December 2025 to coincide with GNR’s 2026 tour announcement. The band had soundchecked “Nothin’” before a Yokohama, Japan concert in May 2025, but Axl Rose and company gave it its proper live debut Saturday at Monterrey’s Parque Fundidora, where the group headlined at the Tecate Pa’l Norte festival: Three songs later, after performing the similarly unearthed track “Perhaps,” GNR played “Atlas,” formerly known as “Atlas Shrugged,” live for the first time.…