Rapper T.I. was forced to miss out on sharing the stage with Lady Gaga at her concert comeback in London on Sunday (01Sep13) because U.K. immigration officials reportedly refused him entry into the country. The pop superstar kicked off the month-long iTunes music festival at the Roundhouse venue over the weekend with her first full stage show since calling off her world tour earlier this year (13) to undergo hip surgery. Instead of playing hits like Born This Way, Paparazzi and Bad Romance, Gaga debuted eight new songs from her forthcoming album ARTPOP, including Jewels & Drugs, her new track with T.I., Too $hort and Twista. However, the Live Your Life hitmaker, who completed his latest prison stint for a probation violation in 2011, was unable to join his collaborators onstage, with Gaga suggesting his previous legal issues were to blame for the travel restriction. Introducing the song, Gaga said, "From across the pond, T.I.! They wouldn't let him into the country, poor thing." She then played a video of T.I. performing his verse, before continuing the tune with personal appearances from Too $hort and Twista.