Taylor Swift and Sabrina Carpenter duet on Nola Eras Tour | Taylor Swift

One of the most anticipated moments from Taylor Swift's Eras Tour concerts is the acoustic segment “Surprise Song.” It comes late in the show, between sections devoted to “The Tortured Poets Department” and “Midnights,” the final chapter.

Swift often brings special guests to help her sing the surprise songs that are never known before and are always a delight for fans.

After singing alone on Friday night, Swift planned the ultimate shocker in New Orleans on Saturday when she called pop superstar Sabrina Carpenter to join her on stage.

Carpenter encouraged Swift to sing her hit “Espresso” on guitar, which she paired with “Is It Over Now.”

“Can I do that?” Swift asked Carpenter.

“You can do it,” Carpenter replied in a short white babydoll dress.

“Oh my God, I'm about to do it,” Swift said, then added the infamous Carpenter line: “I work long hours because I'm a singer.”

But the fun didn't stop there.

The two then sang a mix of “Please, Please, Please” and “Espresso” together while fans shouted the lyrics from their seats.

Swift added that Carpenter was unable to attend the first night of the tour because she only had Saturday off.

Surprise songs on Friday evenings

On Friday, the first of Swift's three sold-out nights at Caesars Superdome in New Orleans, she went to perform her debut album “Our Song,” which she paired with the acoustic guitar mash-up “Call It What You Want” from Reputation.

What followed was a piano mashup of “The Black Dog” from Tortured Poets Department and “Haunted” from 2010’s Speak Now.

This past weekend in Miami, Florence Welch of Florence + the Machine made a surprise appearance with Swift to sing “Florida!!!”; Welch also appeared on the recorded version of the song.

Nola.com reporters Chelsea Shannon and Lauren Walck contributed to this report.