A late penalty from Yeovil substitute Gavin Williams secured all three points for his side against Swansea.
Phillip Jevons aims a shot past Sam Ricketts
Swansea's Garry Monk was sent off for his foul as Phil Jevons bore down on the penalty area in the 84th minute.
Yeovil had goalkeeper Chris Weale to thank for keeping them in the match in the first half as he saved efforts from Roberto Martinez and Andy Robinson.
But the home side improved markedly after the break and the late winner was no more than they deserved.
Yeovil: Weale, Skiverton, Fontaine, Rose, O'Brien, Way,
Terry (Weatherstone 87), Johnson, Gall (Gavin Williams 45),
Jevons, Tarachulski (Stolcers 45).
Subs Not Used: Collis, Caceres.
Goals: Gavin Williams 85 pen.
Swansea: Gueret, Ricketts, Monk, Iriekpen, Austin, Forbes,
O'Leary (Maylett 55), Martinez, Robinson, Trundle,
Connor (Gurney 41), Maylett (Nugent 72).
Subs Not Used: Britton, Fisken.
Sent Off: Monk (84).
Booked: Martinez, Forbes, Robinson.
Ref: J Singh (Middlesex).