The Cymru South's hopes of reaching the UEFA Regions Cup finals are over after a 3-2 defeat to the FA of Vojvodina.
Llantwit Major goalkeeper Jack Lansdown was sent off as Andy Hill's side capitulated again in their second group game in Serbia on Monday.
Back-to-back defeats mean the Welsh representatives will not be able to qualify for the finals in Milan, due to be held at the end of the season.
De Cymru went ahead through an early penalty from Pontypridd United's Liam Eason after eight minutes, before Alex Bonthron (Cwmbran Celtic) doubled their lead with his second goal of the tournament on 62 minutes.
But just three minutes later, an own goal for Josh Allen provided the catalyst for the Serbians to stage a late comeback.
Bratislav Jelic equalised in the 85th minute before Lansdown was shown a straight red card - and his replacement Dion Carroll was beaten by a 96th minute winner from Dejan Mitrovic.
Lansdown's Llantwit teammate, winger Matty Kimmins, was left on the subs bench as the Cymru South's hopes of European silverware came to an end.
De Cymru's final game of this year's tournament sees them face North Macedonia on Thursday afternoon.