Gwen Stefani and Keith Urban joined The Rolling Stones onstage on Friday (03May13) as the rockers officially launched their highly-anticipated U.S. tour in Los Angeles. Hollywood stars Jack Nicholson, Pierce Brosnan, Melanie Griffith and Kelsey Grammer were among the famous faces in the crowd as the Brown Sugar hitmakers kicked off their 50 & Counting trek at the Staples Center. The concert began with a brass performance of (I Can't Get No) Satisfaction by members of the marching band from the University of California, Los Angeles, with Sir Mick Jagger, Ronnie Wood, Keith Richards and Charlie Watts soon emerging to play Get Off Of My Cloud. No Doubt star Gwen Stefani later turned up in a Rolling Stones tank top to perform alongside Jagger on Wild Horses, while country singer Urban was enlisted to play guitar on Respectable. Former Rolling Stone Mick Taylor also made an appearance to play guitar on Midnight Rambler during the group's lengthy set, reports NME.com. Jagger also issued a joking apology to fans after the band had to delay the gig by one day so the Los Angeles Lakers could play at the venue, quipping, "It's either us or the Lakers. So now you got us. It doesn't matter to Jack Nicholson, because he was coming to both of them." The star-studded show followed a surprise gig the Rolling Stones staged in Los Angeles last weekend (27Apr13). The Brits are set to continue their comeback with a string of concerts in North American cities including Las Vegas; Boston, Massachusetts; and Toronto, Canada, before heading to Europe in the summer (13).