A winner early in the second half from Gianni Alioski saw Leeds claim just their third win in 14 matches under former Reds chief Paul Heckingbottom.
Leeds’s head coach was barracked by visiting supporters annoyed by his controversial move from Oakwell to Elland Road just 75 days before.
The game proved an opportunity lost for the third-from-bottom Reds on an afternoon when victory would have seen them climb out of the relegation zone, with fellow strugglers Bolton Wanderers thrashed 4-0 at home by champions Wolves.
It has raised the stakes further ahead of tomorrow’s trip to the City Ground where a win would move Barnsley out of the bottom three ahead of games against play-off candidates Brentford and Derby County.
Morais, who felt that his side should have been awarded a second-half penalty when Adam Hammill went down under a challenge from Matthew Pennington, said: “I believe that the players need to lift up their heads and bodies in thinking forward. Winning this game can put us in a position out of the relegation zone and into a position where we can stay in the league.
“After that we can manage the results in terms of having the same results as the other teams behind. The next one is a very important game. We still have this possibility (game) in hand and this is what we want to take. We have to move forward and there is nothing we can do to make a different result in this (Leeds game).
“We expected to claim a good result. My belief is that we should have been rewarded with something more from this game, but it was not possible.
“We had enough opportunities to make it a different result, at least level the game, and we had a penalty situation which the referee did not see. It was a clear penalty.”
There was relief for Morais’s counterpart Heckingbottom, who elected to forego his press duties after the game.
His No 2 Jamie Clapham, who was also with him at Oakwell, addressed the media and said: “I obviously cannot answer for Paul, but, for me, it is great to get three points.
“It was an emotional day leading up to the game because everywhere you go and work there are a lot of good people within football clubs and Barnsley is no different.
“It added to the game because of who it was against and where we had come from. It was only something you would expect, but I am sure he (Heckingbottom) is down there delighted with the three points as I am.”
Much-derided director of football Victor Orta is set to remain in his job at Leeds after rejecting an approach from Deportivo La Coruna to become their new sporting director.
There was some good news to emerge from South Yorkshire, however, as Rotherham United clinched a place in the League One play-offs with two games to spare after a 2-0 home win against Bristol Rovers.
Millers manager Paul Warne said: “If they can perform to their level we’ll have a right chance against anyone over two games.
“It’s cup football really. You could be the best team over the two games. It doesn’t mean you’re going to win the tie and get through. I hope that if we don’t go through it’s because the other team is better not that we were unlucky.”