The midfielder made way as Benjelloun entered the game at half-time.
"Michael was struggling and felt poorly," explained Collins.
"He wanted to stay on, but we felt that it would be better for him to come off.
"It was a very even first-half, but Michael scored a great goal that came at the right time for us just before the break."
Hibs striker Steven Fletcher revealed that Collins had also challenged him to grab his chance after Chris Killen was ruled out for the season.
"The gaffer pulled me aside and said this is my chance and that I should go out and take it," said Fletcher.
The Scotland Under-19 international responded with a goal and a man-of-the-match award against Aberdeen.
"We have been playing well in recent weeks without getting results," he said.
"But this time all the hard work paid off."
Hibs have earned themselves a fourth-round tie at home to First Division leaders Gretna.
"They have gone through the leagues and shown they are a good side, so it is going to be a hard game at Easter Road," added Fletcher.