In addition to Snoop Lion and Rita Ora, Jay-Z and Justin Timberlake are also on the packed bill at this weekend’s Yahoo! Wireless Festival in London. Although he has his own headlining slot later tonight, Hov joined JT on the main stage last night to help him perform their “Suit & Tie” hit. Justin also played his new single, “Take Back the Night,” live for the first time.

Consider this a rehearsal for the two Js’ Legends of the Summer Stadium Tour, which gets underway on Wednesday (July 17) in Toronto.

Watch Justin Timberlake perform “Take Back the Night” after the jump…

New Music: Jay-Z Feat. Justin Timberlake “Holy Grail”
New Music: Justin Timberlake “Take Back the Night”
New Music: Jay-Z “Dead Presidents 3″ (Original Version)