Barnsley manager Paul Heckingbottom felt his side deserved some reward for their display at Molineux.
Substitute Alfred N’Diaye grabbed a stoppage-time winner for the hosts after Barnsley defender Adam Jackson’s 90th-minute goal had cancelled out Bright Enobakhare’s opener 10 minutes previously.
Heckingbottom thought the Reds were hard done by not to have been awarded a first-half penalty after Wolves captain Danny Batth appeared to push over Tom Bradshaw.
Heckingbottom said: “Yes, it’s a penalty. I’m not here to talk about refs, but they always find a way into the headlines and most of the times it is when they don’t do their job properly.
“There were not too many things wrong from our point of view in terms of what we are asking the players to do.
“We knew we were playing against a good side with lots of good players, so we knew we had to be organised, perform properly and we did for the majority.
“We deserved at least a point and we thought we’d got it, so it’s a sickener. It was just a moment of us switching off.
“If you compare the teams, they’ve got £16m players, we’ve got players from lower-league and non-league, youth under-23 teams, but that’s credit to our players because they enjoy competing against players who have been bought for big money.
“There’s lots of positives, but we’ve not got the experience in our team to win games ugly at the minute.”
Wolverhampton Wanderers: Ruddy, Batth, Coady, Roderick Miranda, Doherty, Saiss (N’Diaye 80), Neves, Ruben Vinagre (Douglas 46), Ivan Cavaleiro (Enobakhare 65), Leo Bonatini, Jota. Unused substitutes: Marshall, Helder Costa, Price, Norris.
Barnsley: Davies, McCarthy, Jackson, Lindsay, Pearson, Joe Williams, Hammill, Moncur (McGeehan 82), Potts (Ugbo 82), Barnes (Hedges 70), Bradshaw. Unused substitutes: MacDonald, Townsend, Pinnock, Thiam.
Referee: J Simpson (Lancashire).