Jennifer Lopez joins Taylor Swift on stage

As part of Taylor Swift's Red Tour, she's had stars pop up on stage with her on various stops.

Now, adding to a list that includes Ellie Goulding, Tegan & Sara, Sara Bareilles and Chery Lloyd, Jennifer Lopez rocked the Staples Center stage on Saturday night.

On the fourth night of TSwift's sold-out L.A. run, she asked the crowd: "So I'm just wondering, Los Angeles, how would you feel if there was a special surprise guest?"

Enter Jenny From the Block.