Taylor Swift was joined by surprise guest Florence Welch for her first live performance of "Florida!!!" during the final European date of her Eras tour on Tuesday.
The pop megastar also debuted "So Long, London", a ballad that fans widely believe is about the end of her relationship with British actor Joe Alwyn, in the acoustic section of the show at Wembley Stadium.
Both tracks feature on Swift's eleventh studio album, "The Tortured Poets Department", which was released this year.
Welch, of British indie rock band Florence + the Machine, co-wrote "Florida!!!" and sang on the recorded track.
Swift drew fans from near and far for the last opportunity to see her critically acclaimed show in Europe.
The US singer-songwriter returned to London's Wembley Stadium last week for five performances following the cancellation of her shows in Vienna, when a planned attack was foiled by authorities.
Some of the 195,000 disappointed fans in Vienna rushed to buy tickets for the London dates on resale sites, where they were changing hands for up to 10 times face value.
Eras, the first tour to surpass $1 billion in revenue, showcases all 11 of Swift's studio albums in dedicated sections. Her performances and the show's staging have been praised by critics.
Fans arriving in Wembley, dressed in sequins, cowboy hats, and forearms covered in friendship bracelets ready to swap with other Swifties, faced tight security checks.
While British police have said there was nothing to indicate the events in Vienna would impact any of the shows at Wembley, there was highly visible security at the stadium.
Tay-gating, the practice of gathering outside a Swift show without a ticket, as thousands did in Munich last month, has been banned, as authorities try to reduce harder-to-control risks outside the venue.
Marie Wright, aged 48, from Limerick, Ireland, bought tickets on a resale site on Monday evening and flew to London on Tuesday with her daughter’s best friend Aoife McCarthy, aged 15. Her own daughter had already seen the show in Dublin.
"She’s going to leave Europe, so we had to come for the last night," McCarthy said.
"Her songs have real meaning and there’s a poetry to them," Wright added.
The tour returns to the United States in October and ends in Vancouver, Canada, in December.
