Barnsley boss Valerien Ismael says he was always confident that his second half substitutes would be the difference maker.
Ismael made one change at the break, a triple switch 10 minutes into the second half and by the 64th minute, the Barnsley boss had used all five of his replacements.
Morris had a decisive impact, scoring the opener with 18 minutes to play and then setting up Alex Mowatt in the final minute.
And Ismael, whose side climbed above Rovers with the win, said: “We knew with the schedule and our squad depth that we have more possibilities to do something.
“We knew at half-time that the bench would win the game. I told the guys we had to stay in the game and change some situations and make more pressure.
“We have a big impact from the five players who came on and scored in the right moment. Maybe after the 1-0, we had a lot of opportunities to finish the job and we were too sloppy with the last pass.
“But finally Alex scored with an important goal in that moment.
“That is why we worked on the squad when we came and we knew we had to do something in the transfer window and you could see how important it was to do something as it was the game-changer to make something.”
The one disappointment for Ismael was that they couldn’t hold out for back-to-back clean sheets as Adam Armstrong scored in the fourth minute of injury time.
That was just a third shot on target of the night for Rovers however, and Ismael added: “Then to concede a goal was completely unnecessary at that moment with two minutes to play and we have to be more clinical.
“We made a mistake, but it is not the big deal because we won. We got the three points and keep moving in the table and we keep the momentum on our side now and it is important in that situation.”
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