An 88th-minute winner from Maliq Cadogan gave 10-man Swansea City Under-21s a vital three points and boosted their Professional Development League play-off aspirations against Sheffield Wednesday at Hillsborough.
The visitors had Filip Lissah dismissed in the 17th minute for a foul on Bruno Fernandes, but the Swans had the better of the chances in south Yorkshire.
But substitute Cadogan would seal the three points late on as he finished after receiving a Kyrell Wilson lay-off.
Swansea had shown five changes from their meeting with Burnley, with Evan Watts, Aimar Govea and Iestyn Jones among those to come into the team.
The opening stages of the game were cagey, although Fernandes had en effort saved after breaking through in midfield.
Wednesday keeper Pierce Charles did well to deny Ben Lloyd as the keeper recovered having raced off his line to clear from Wilson.
Swansea had a good spell following that opening, Govea sent a header flashing wide before Cameron Congreve had his free-kick saved.
But the visitors were reduced to 10 just before the 20-minute mark, with Lissah seeing red after catching the heels of Fernandes as they chased a through ball.
The Owls looked to capitalise on the numerical advantage, but Jones cleared two efforts from Jay Buchan and Fernandes respectively.
Good link-up between Govea and Wilson ended with the latter flashing his final effort just wide.
Wilson was involved again moments later after the forward was picked out by a superb ball by Josh Carey, but his effort flew over the bar.
The Swans started the second period strongly, Wilson driving goalward once more from a Mitchell Bates pass, before sending his close-range effort straight into the hands of Charles.
At the other end, Watts was called into action when Fernandes' long-distance strike stung the palms of the Wales youth international, before he was on hand to deny Buchan's effort from inside the six-yard box.
The hosts spurned multiple chances in the closing stages. Favour Onukwuli causing trouble down the right flank before cutting inside, but his efforts were no bother for Watts.
But the Swans would snatch the victory with just minutes remaining.
Wilson broke quickly from a Wednesday corner, beating three defenders before laying off for Cadogan to find the net after his initial effort was saved by Charles.
Swansea City Under-21s: Evan Watts, Iestyn Jones, Josh Carey (Jacob Cook 85'), Mitchell Bates, Filip Lissah (captain), Kian Jenkins, Kyrell Wilson, Glory Nzingo (Harlan Perry 25), Ben Lloyd, Aimar Govea (Maliq Cadogan 58)
Substitutes: Remy Mitchell, Thomas Woodward.