A Nelly/T.I. joint show would’ve been a much bigger deal a decade ago, but it’s still a hot ticket. The uniquely melodic sound of Nelly’s debut, Country Grammar, put St. Louis on the rap map in 2000, beginning a half-decade run on the charts that few if any rappers since have topped. Nelly’s past 10 years have been more hit-or-miss, though he’s had his successes with the 2010 single “Just a Dream” and the better experiments of 2013’s stylistically varied M.O., which incorporated country, funk, and EDM. T.I. has had one of the more pronounced evolutions in rap history: He originated trap-rap in Atlanta in the early ’00s, rocketed to superstar status later in the decade with hits like the synth-rap classic “What You Know,” and eventually transformed into the conscious rapper he is today. Last year’s sharply race-aware Us or Else: Letter to the System proved the latter period suits him well.