Jermain Defoe scored a hat trick as Sunderland won a thrilling Premier League relegation battle at Swansea.
The Black Cats' 4-2 victory was mired in controversy as they recovered from a 2-1 half-time deficit to claim a second successive league win, offering real hope of avoiding the drop.
Sunderland's victory took them above neighbours Newcastle on goal difference and to within a point of Swansea, who were reduced to 10 men when Kyle Naughton was sent off close to half-time with the score at 1-1.
Graham Scott, a late replacement for Andre Marriner on Monday, was taking charge of only his fourth top flight fixture -- and the Oxfordshire official was in the spotlight for most of the night, with several big calls to make.
Defoe's first two goals stood despite him being perilously close to offside on both occasions, while Scott awarded Swansea a first-half penalty which appeared generous in the extreme and then sent off Naughton in contentious fashion.
Sunderland were gifted the perfect start after three minutes when Lukasz Fabianski's loose ball was collected by Adam Johnson and his pass found Fabio Borini.
The former Swansea striker's shot was too hot for Fabianski to hold, and Defoe was on the spot to tap into an empty net to score against the Welsh club for the third consecutive game.
Swansea were visibly shaken and things almost got worse when Patrick van Aanholt raided down the left to deliver a cross which the unmarked Johnson sent wide.
But Swansea were handed a lifeline when Andre Ayew broke into the box and won a dubious penalty after appearing to kick the floor in the act of shooting.
Wes Brown was adjudged to have made the most marginal of contact, but Sigurdsson stroked home the penalty with the minimum of fuss.
Swansea were reduced to 10 men when Naughton was punished for a 37th-minute challenge on Yann M'Vila. The defender's studs were showing but heclearly took the ball and the theatrical reaction of the France international did him few favours.
However, Ayew almost instantly sprinted into space, shrugged off Lee Cattermole and buried a powerful low shot through the legs of Billy Jones and into the far corner of the net.
Swansea manager Alan Curtis instantly withdrew Leon Britton on the occasion of the midfielder's 500th appearance for the club as Angel Rangel filled Naughton's right-back position.
But Sunderland were level four minutes after the restart when Van Aanholt's drive took a telling deflection off Federico Fernandez and flew past Fabianski off a post.
Jermain Lens struck an upright from a tight angle as Sunderland came on strongly, and Defoe put them ahead just after the hour when he was adjudged onside from Johnson's pass and finished expertly.
Rangel was not so fortunate when he bundled the ball home after Vito Mannone had spilled Sigurdsson's deflected shot on his goal-line.
And Sunderland wrapped up the points when Defoe was again in the right place to finish van Aanholt's cross from a few yards out four minutes from time.