ZZ Top had previously served as Guns N' Roses' opening act during the reunited act's recent stretch of tour dates. During Friday's encore, Gibbons added his unique touch to a guitar solo on the Lies ballad as he performed alongside Slash and Duff McKagan.
Throughout the concert, Rose kept rallying the Toyota Center crowd with "Houston Strong," the city's slogan in the aftermath of Hurricane Harvey, which also impacted ZZ Top, the Houston Press reports.
The Not in This Lifetime tour – which will continue into 2018 after the "classic" lineup announced a slate of European dates, including festival-headlining gigs – has produced its share of surprises since embarking in April 2016, from Angus Young appearances and Pink duets to unexpected covers of Soundgarden's "Black Hole Sun" and Glen Campbell's "Wichita Lineman."
Guns N' Roses' current run of North American dates concludes November 29th with a hometown show at Los Angeles' the Forum. Six months later, Axl Rose and company will reconvene for the six-week 2018 European leg.