The Swans were brought back down to earth with a bang following their win over Arsenal as they slipped to a 2-0 defeat at Sunderland.
The scoreline was a harsh reflection on the Swans' performance, as they enjoyed the majority of possession and territory.
Stephane Sessegnon put Martin O'Neill's side ahead with a fine finish in the 14th minute before substitute Craig Gardner finished the game off with an excellent strike from around 30 yards late on.
The Swans made just one change to the side that beat Arsenal as Gylfi Sigurdsson made his first start.
The Icelandic international went into midfield in place of Kemy Agustien, who dropped to the bench while new arrival Josh McEachran was also among the substitutes following his loan move from Chelsea.
Sunderland: Simon Mignolet, Phil Bardsley, John O'Shea, Wes Brown, Kieran Richardson, Lee Cattermole (capt), David Vaughan (Craig Gardner, 79), Sebastian Larsson (Ahmed Elmohamady, 89), James McClean, Stephane Sessegnon, Nicklas Bendtner (Connor Wickham, 12).
Subs: Kieren Westwood, David Meyler, Ji Dong-won, Michael Turner.
Swans: Michel Vorm, Angel Rangel, Steven Caulker, Ashley Williams (capt), Neil Taylor, Leon Britton (Wayne Routledge, 79), Joe Allen, Gylfi Sigurdsson (Josh McEachran, 66), Nathan Dyer, Scott Sinclair, Danny Graham.
Subs: Gerhard Tremmel, Jazz Richards, Garry Monk, Kemy Agustien, Luke Moore.
Referee: Chris Foy
At a windy Stadium of Light, the hosts almost got off to a flying start as Kieran Richardson found Sebastian Larsson at the back post with a deep cross, and his volley was well kept out by Michel Vorm courtesy of a fine low save.
That came either side of chances for Nathan Dyer and Scott Sinclair following through balls from Gylfi Sigurdsson, but the Sunderland defence snuffed out the danger.
Home boss Martin O'Neill was forced into an early change as Connor Wickham replaced Nicklas Bendtner, who had suffered a facial injury.
The Swans then went close to taking the lead as another superb Sigurdsson through ball found Dyer, and his cross along goal missed Danny Graham but found Sinclair, but he fired over from 12 yards.
Moments later, Sunderland took their chance and took the lead after 14 minutes. Stephane Sessegnon worked some magic in the box and after a one-two in the box he curled his effort past Vorm and into the top right-hand corner.
The Swans responded with Graham heading over from Sigurdsson's cross before the Icelandic midfielder then saw his effort bounce just wide of the far post.
Sigurdsson then saw another fly wide before Graham's effort whistled over the far post.
Half-time: Sunderland 1 Swans 0
There were no changes at the break, and the Swans started the more positive of the sides as Sunderland were forced on the backfoot.
Sigurdsson saw a free-kick parried by Simon Mignolet before he was replaced by Josh McEachran just after the hour.
The Swans continued to dominate possession and territory, but they just couldn't carve open the Sunderland defence.
In a rare attack, Sunderland went close to doubling their lead as Sessegnon headed just wide following James McClean's quick counter and cross.
Leon Britton saw his 20-yard effort bounce harmlessly wide in what was his final act as Wayne Routledge took his place for the last ten minutes.
Wickham then missed a great chance from close range to settle the game, while at the other end Sinclair drove his effort high and wide.
Moments later, the game was over.
Sessgnon found substitute Craig Gardner 30 yards out, and the midfielder drilled home a superb strike into the left corner with Vorm helpless.