Demi Lovato made a surprise appearance at the kickoff to the Jonas Brothers‘ 20th anniversary tour at MetLife Stadium in East Rutherford, N.J., on Sunday. The singer wore pieces styled by Acne Studios and Rui Zhou for the concert.

Lovato’s look, curated by stylist Chris Horan, evoked contemporary pop star style with Y2K references while seamlessly coordinating with each Jonas Brothers’ look, too.

The “Cool for the Summer” singer wore a pair of high-waist, super-wide-leg denim-style Acne Studios pants with allover shimmering details that sparkled under the stage lights.

The tone of the pants gave off a dusty gold hue. Lovato coordinated the pants with a top by Rui Zhou. The cropped, bikini-silhouette top featured a plunging neckline and was tied at the back. The color coordinated with Lovato’s pants and complemented Joe Jonas’ chocolate brown concert wardrobe. Nick, Kevin and Joe Jonas were styled by Sydney Lopez.

During the concert, which marked the start of band’s Jonas20 tour, Lovato and Joe Jonas gave concert-goers a dose of nostalgia. The singers performed “This Is Me” and “Wouldn’t Change a Thing” from the Disney Channel original movie “Camp Rock,” which stars the former Disney talents and debuted in 2008.

Along with her Acne Studio pants and a Rui Zhou top combination, Lovato’s glam highlighted her pop star style sensibility. The singer’s raven black hair was styled with the controversial side part and featured cascading waves down her shoulders.

Horan is well-versed in dressing pop stars. The stylist has also worked with Charli XCX and Christina Aguilera, among others. Horan previously styled Lovato in pieces by SRVC.

Y2K-inspired styles coincide with a rise in early aughts nostalgia. From “Freakier Friday,” the sequel to 2003’s “Freaky Friday,” to style trends like low-rise jeans, ballet flats and more on the rise, the 2000s found new cultural relevance on stage, screen and street styles.