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Gwen Stefani helped the Rolling Stones get things started in Los Angeles this weekend.

The iconic rockers kicked off their "50 and Counting" trek Friday night, and says the No Doubt frontwoman joined them for a duet version of "Wild Horses."

But Stefani -- who came dressed for the part in a shirt featuring a giant sparkly version of the Stones' tongue logo -- wasn't the only special guest. Country star Keith Urban also took the stage with Mick Jagger and company, as did former Stones guitarist Mick Taylor.

The Rolling Stones are scheduled to continue their outing with a stop in San Jose, California on Wednesday, while Stefani and the rest of No Doubt are still in the studio working on the follow-up to last year's comeback album, Push and Shove.