The Swans went down 3-2 at Bournemouth as their winning run came to an end on the south coast.
The visitors had to come from behind on two occasions after Max Gradel fired into the bottom corner after 37 minutes.
The Swans were soon back on level terms as Modou Barrow became the first Gambian to score in the Premier League as he cut inside before curling low into the net.
After the break, the goals flowed.
The lively Joshua King drilled in via the near post to put Bournemouth ahead once again, but the Swans were level on 63 minutes as Sigurdsson scored his seventh goal in 11 games from Barrow's low cross.
In a final push, it was the Cherries who bagged victory as Steve Cook nodded home from a quickly-taken corner.
Defeat left the Swans on 33 points after 30 games - eight points clear of the dropzone.
The Swans made two changes to the starting XI.
From the win over Norwich City last weekend, Leroy Fer went into midfield in place of Leon Britton, while Modou Barrow earned a start in place of Andre Ayew, who was nursing an ankle injury.
Ki Sung-Yueng was included on the bench after missing the 1-0 victory over the Canaries at the Liberty, but Jefferson Montero did not travel as he was suffering with flu.
AFC BOURNEMOUTH: Artur Boruc, Simon Francis (capt), Steve Cook, Dan Gosling (Eunan O'Kane, ht), Andrew Surman, Max Gradel (Marc Pugh, 76), Charlie Daniels, Adam Smith, Joshua King, Benik Afobe (Lewis Grabban, 66), Matt Ritchie.
SUBS: Adam Federici, Tommy Elphick, Juan Iturbe, Sylvain Distin.
SWANS: Lukasz Fabianski, Angel Rangel, Federico Fernandez, Ashley Williams (capt), Neil Taylor, Jack Cork, Leroy Fer (Ki Sung-Yueng, 84), Gylfi Sigurdsson, Modou Barrow (Marvin Emnes, 79), Wayne Routledge (Bafe Gomis, 60) Alberto Paloschi.
SUBS: Kristoffer Nordfeldt, Kyle Naughton, Jordi Amat, Leon Britton.
It was the hosts who set the early pace at the Vitality Stadium, with the lively Joshua King nodding over from Max Gradel's cross after three minutes.
At the other end, Wayne Routledge volleyed over after Jock Cork headed a Gylfi Sigurdsson free-kick into his path.
King then wasted a decent chance to open the scoring when he blasted over from ten yards out before Bournemouth went even closer as Andrew Surman struck the outside of the post from a 20-yard free-kick.
The Swans responded through Federico Fernandez, who headed a Sigurdsson free-kick wide, while the Icelandic midfielder drilled a low shot off target soon after.
The deadlock was broken after 37 minutes, with Lukasz Fabianski parrying an Adam Smith cross, and Gradel drilled his low effort in the bottom corner from close range.
The Swans needed an instant response, and they got just that two minutes later.
It came through Modou Barrow, who cut inside from the right flank before drilling a low effort into the bottom far corner.
The goal gave the Swans more belief, and Routledge fired a low half-volley just wide in the dying moments as both teams went into the break on level terms.
HALF-TIME: Bournemouth 1 Swans 1
There was plenty more action to come in the second half, and Bournemouth were quick out of the blocks once again.
Just five minutes after the restart, the hosts were ahead as Gradel intercepted Leroy Fer's pass before finding King, and he rifled in his effort off the near post despite Fabianski getting a hand to it.
The Swans were back on level terms once again though, as sub Bafe Gomis held up the ball before touching wide to Barrow, whose cross was controlled and fired home by Sigurdsson.
it was thrilling stuff, and the Swans almost found themselves ahead just a minute later as Alberto Paloschi got onto the end of another Barrow cross, only to be denied by keeper Artur Boruc.
From the resulting corner, Fer rose highest to nod towards goal, only for Gomis to volley wide.
Paloschi then saw his half-volley on the turn padded out by Boruc in a promising spell for the visitors.
But that spell ended in the 78th minute after Ashley Williams expertly denied King by thwarting his effort out for a corner. The Cherries worked a quick delivery, and the unmarked Steve Cook nodded home.
It could have got worse for the Swans, but Fabianksi reacted quickly to tap sub Lewis Grabban's chip over the crossbar.