While Yeovil manager Russell Slade was left fuming at Frimley official Paul Melin's decision to not only penalise Terrell Forbes for hauling down Adebayo Akinfenwa, the referee also dished out one of the night's seven yellow cards to the central defender.
Up until that moment the night had been destined to be Yeovil's following a dream debut from former Premiership striker Marcus Stewart. The man who has more than £7million worth of transfers in his past joined Yeovil on loan from Bristol City and didn't take long to make his mark.
Having forced Alan Tate to clear from his own line as the ball seemed destined to hit the net shortly after the break, Stewart hit the mark three minutes later with a stooping header that left Willy Gueret with no chance in the home goal.
That was nothing less than Yeovil deserved having frustrated Swansea for the first 40 minutes before exploding into action at the end of the first half and forcing Gueret to save twice before the interval.
The home side were pleased to be able to welcome back midfielders Andy Robinson and Leon Britton after injuries and Robinson quickly settled into his customary role of chief playmaker as he urged his side forward in the opening exchanges.
It was his free kick from the edge of the area that forced the first save of the night after six minutes when Steve Mildenhall had to dive to his left to keep the ball out of his top corner.
But if the Swans enjoyed the better of the early possession and play it was Yeovil, who arrived boasting a superior league position following their home win over Port Vale the previous weekend, who ended the first half stronger and more organised.
A low shot from Lee Morris forced Gueret to push the ball onto his right hand post after 16 minutes to liven up proceedings and then Melin had to lay down the law. He issued yellow cards in quick succession to Yeovil's Paul Terry and Swansea's Tom Williams for reckless challenges and Williams earned an extra telling off for some back chat moments later.
But Terry's strength and commitment in front of the back four came more and more into the game as he broke up home attacks and lunched a number of counter offences.
While Swansea were unable to get star striker Trundle into the clear, Terry and his energetic flank men began to create chances at the other end.
Yeovil had three great chances at the end of the half as they forced two good saves out of Gueret. A Wayne Gray header was pushed over the top by the keeper who then had to take the sting out of a Lee Morris shot from the edge of the area.
It was more of the same from Yeovil at the start of the second half and that Stewart goal gave them a well deserved lead. But the subtle introduction of Akinfenwa by Swansea manager Kenny Jackett made a huge difference to the home attack and, when Forbes wrapped him up in a bear hug after 62 minutes, the penalty gave Trundle the chance he was looking for.
Up until then Trundle and the rest of his attacking colleagues had been well and truly neutered. But making light of his spot miss at Oldham last month - one of two penalties the Swans have missed this season in the wake of May's Play-off final penalty shoot out defeat at the Millennium Stadium - he smashed the ball past Mildenhall.