But it was a measure of the Colombian striker’s growing maturity and more rounded capabilities under Giovanni van Bronckhorst that his reaction was so positive and effective as Rangers produced a memorable second half display in defeating the Bundesliga side 6-4 on aggregate in their Europa League knockout round play-off tie.
Morelos struggled to impose himself on proceedings as Dortmund overcame James Tavernier’s spot-kick opener for the hosts to lead 2-1 at the break and reduce their overall deficit to a single goal.
But the 25-year-old was transformed after the interval, causing the Dortmund defence no end of grief with his strength and movement as he linked up dynamically with winger Ryan Kent in Rangers’ rejigged 3-5-2 formation.
Van Bronckhorst doesn’t attempt to gloss over Morelos’ failings in the opening period but the Rangers manager is fulsome in his general praise of a player who seems to be in as contented a place as he has ever been since joining the Ibrox club.
"Alfredo had a better second half than first half,” said van Bronckhorst. "At the beginning of the first half, he had some problems with the physicality of the Dortmund defenders.
"He lost too many balls when he had to control them. In the second half, he was much more dominant like we know him.
"You can see that once he has the ball and keeps the ball, we can move from him with runs from Ryan Kent and midfield.
"I am really happy with his body language - his whole performance and the way he shines. He has to keep that momentum going, along with all the other players.”
Van Bronckhorst is dismissive of suggestions it will be difficult for his team to maintain that momentum and level of intensity when they return to domestic business against Motherwell at Ibrox on Sunday.
“No, I don’t think so,” he said. “It doesn’t matter which competition you play, you have to be ready from the first minute. So I think the transition will be easy.”