Fellow substitutes Josh Sims and Sofiane Boufal were involved in the build up to the Italian's equaliser. And Pellegrino understands how important the changes will be as his side look to avoid relegation.
"I think so, I think the substitutions make a big impact on the team," said the Saints manager.
"Josh because he is an intelligent guy, running behind and being always close to the strikers and was really close to score.
"Sofiane allow us to have three or four free kicks in the frontal area and Manolo scored the goal.
"It's important when the team has got people from the bench ready mentally because in this type of game when it's really really tough the substitution can be important."