Swansea City suffered a first defeat in Cardiff since 2012, as two second half goals secured all three points for the Bluebirds.
Swans manager Michael Duff named new signings Josh Tymon, Kristian Pedersen and Jamal Lowe in the starting line-up, as Joe Allen was withdrawn after suffering a groin injury in the warm up.
After a goalless first half, Cardiff substitute Ollie Tanner scored just seconds after being introduced, before a harshly awarded penalty saw Bluebirds and Wales captain Aaron Ramsey add a second from the penalty spot with just five minutes remaining.
The Swansea City return to Championship action on Tuesday evening, when they travel to London to play Queens Park Rangers.
Team Lineups
Swansea City: Carl Rushworth; Harry Darling, Nathan Wood, Kristian Pedersen (Mykola Kuharevich 90); Josh Key, Jay Fulton (Ollie Cooper 90), Matt Grimes (captain), Charlie Patino (Liam Cullen 82), Josh Tymon; Jerry Yates (Josh Ginnelly 63), Jamal Lowe (Jamie Paterson 63).
Unused Substitutes: Andy Fisher, Ben Cabango, Harrison Ashby, Bashir Humphreys.
Cardiff City: Jak Alnwick, Dimitrios Goutas, Mark McGuinness, Ryan Wintle, Aaron Ramsey (captain) (Callum Robinson 90), Ike Ugbo (Ollie Tanner 70), Karlan Grant, Jamilu Collins, Yakou Meite (Kion Etete 81), Manolis Siopsis, Perry Ng.
Unused Substitutes: Alex Runarsson, Joe Ralls, Ebou Adams, Jonathan Panzo, Rubin Colwill, Andy Rinomhota.
Referee: Samuel Barrott
Match Highlights
Watch highlights of the Swans defeat at the Cardiff City stadium.
Feature Image Credit: Swansea City Football Club